Inbred corn line PHCWK

ABSTRACT

A novel inbred maize line designated PHCWK and seed, plants and plant parts thereof. Methods for producing a maize plant that comprise crossing inbred maize line PHCWK with another maize plant. Methods for producing a maize plant containing in its genetic material one or more traits introgressed into PHCWK through backcross conversion and/or transformation, and to the maize seed, plant and plant part produced thereby. Hybrid maize seed, plant or plant part produced by crossing the inbred line PHCWK or an introgressed trait conversion of PHCWK with another maize line. Inbred maize lines derived from inbred maize line PHCWK, methods for producing other inbred maize lines derived from inbred maize line PHCWK and the inbred maize lines and their parts derived by the use of those methods.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/769,207 filed on Jan. 30, 2004, the contents of which are herebyincorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention relates generally to the field of maize breeding,specifically relating to an inbred maize line designated PHCWK.

BACKGROUND OF THE INVENTION

The goal of plant breeding is to combine, in a single variety or hybrid,various desirable traits. For field crops, these traits may includeresistance to diseases and insects, tolerance to heat and drought,reducing the time to crop maturity, greater yield, and better agronomicquality. With mechanical harvesting of many crops, uniformity of plantcharacteristics such as germination, stand establishment, growth rate,maturity, plant height and ear height, is important. Traditional plantbreeding is an important tool in developing new and improved commercialcrops.

SUMMARY OF THE INVENTION

According to the invention, there is provided a novel inbred maize line,designated PHCWK and processes for making PHCWK. This invention relatesto seed of inbred maize line PHCWK, to the plants of inbred maize linePHCWK, to plant parts of inbred maize line PHCWK, and to processes formaking a maize plant that comprise crossing inbred maize line PHCWK withanother maize plant. This invention also relates to processes for makinga maize plant containing in its genetic material one or more traitsintrogressed into PHCWK through backcross conversion and/ortransformation, and to the maize seed, plant and plant part produced bysuch introgression. This invention further relates to a hybrid maizeseed, plant or plant part produced by crossing the inbred line PHCWK oran introgressed trait conversion of PHCWK with another maize line. Thisinvention also relates to inbred maize lines derived from inbred maizeline PHCWK, to processes for making other inbred maize lines derivedfrom inbred maize line PHCWK and to the inbred maize lines and theirparts derived by the use of those processes.

Definitions

Certain definitions used in the specification are provided below. Alsoin the examples that follow, a number of terms are used herein. In orderto provide a clear and consistent understanding of the specification andclaims, including the scope to be given such terms, the followingdefinitions are provided. NOTE: ABS is in absolute terms and % MN ispercent of the mean for the experiments in which the inbred or hybridwas grown. PCT designates that the trait is calculated as a percentage.% NOT designates the percentage of plants that did not exhibit a trait.For example, STKLDG % NOT is the percentage of plants in a plot thatwere not stalk lodged. These designators will follow the descriptors todenote how the values are to be interpreted.

ABTSTK=ARTIFICIAL BRITTLE STALK. A count of the number of “snapped”plants per plot following machine snapping. A snapped plant has itsstalk completely snapped at a node between the base of the plant and thenode above the ear. Expressed as percent of plants that did not snap.

ALLELE. Any of one or more alternative forms of a genetic sequence.Typically, in a diploid cell or organism, the two alleles of a givensequence typically occupy corresponding loci on a pair of homologouschromosomes.

ANT ROT=ANTHRACNOSE STALK ROT (Colletotrichum graminicola).

A 1 to 9 visual rating indicating the resistance to Anthracnose StalkRot. A higher score indicates a higher resistance.

BACKCROSSING. Process in which a breeder crosses a hybrid progeny lineback to one of the parental genotypes one or more times.

BARPLT=BARREN PLANTS. The percent of plants per plot that were notbarren (lack ears).

BREEDING. The genetic manipulation of living organisms.

BREEDING CROSS. A cross to introduce new genetic material into a plantfor the development of a new variety. For example, one could cross plantA with plant B, wherein plant B would be genetically different fromplant A. After the breeding cross, the resulting F1 plants could then beselfed or sibbed for one, two, three or more times (F1, F2, F3, etc.)until a new inbred variety is developed. For clarification, such newinbred varieties would be within a pedigree distance of one breedingcross of plants A and B. The process described above would be referredto as one breeding cycle.

BRTSTK=BRITTLE STALKS. This is a measure of the stalk breakage near thetime of pollination, and is an indication of whether a hybrid or inbredwould snap or break near the time of flowering under severe winds. Dataare presented as percentage of plants that did not snap.

CELL. Cell as used herein includes a plant cell, whether isolated, intissue culture or incorporated in a plant or plant part.

CLDTST=COLD TEST. The percent of plants that germinate under cold testconditions.

CLN=CORN LETHAL NECROSIS. Synergistic interaction of maize chloroticmottle virus (MCMV) in combination with either maize dwarf mosaic virus(MDMV-A or MDMV-B) or wheat streak mosaic virus (WSMV). A 1 to 9 visualrating indicating the resistance to Corn Lethal Necrosis. A higher scoreindicates a higher resistance.

COMRST=COMMON RUST (Puccinia sorghi). A 1 to 9 visual rating indicatingthe resistance to Common Rust. A higher score indicates a higherresistance.

CROSS POLLINATION. A plant is cross pollinated if the pollen comes froma flower on a different plant from a different family or line. Crosspollination excludes sib and self pollination.

CROSS. As used herein, the term “cross” or “crossing” can refer to asimple X by Y cross, or the process of backcrossing, depending on thecontext.

D/D=DRYDOWN. This represents the relative rate at which a hybrid willreach acceptable harvest moisture compared to other hybrids on a 1 to 9rating scale. A high score indicates a hybrid that dries relatively fastwhile a low score indicates a hybrid that dries slowly.

DIPERS=DIPLODIA EAR MOLD SCORES (Diplodia maydis and Diplodiamacrospora). A 1 to 9 visual rating indicating the resistance toDiplodia Ear Mold. A higher score indicates a higher resistance.

DIPLOID PLANT PART. Refers to a plant part or cell that has the samediploid genotype as PHCWK.

DIPROT=DIPLODIA STALK ROT SCORE. Score of stalk rot severity due toDiplodia (Diplodia maydis). Expressed as a 1 to 9 score with 9 beinghighly resistant.

DRPEAR=DROPPED EARS. A measure of the number of dropped ears per plotand represents the percentage of plants that did not drop ears prior toharvest.

D/T=DROUGHT TOLERANCE. This represents a 1 to 9 rating for droughttolerance, and is based on data obtained under stress conditions. A highscore indicates good drought tolerance and a low score indicates poordrought tolerance.

EARHT=EAR HEIGHT. The ear height is a measure from the ground to thehighest placed developed ear node attachment and is measured incentimeters.

EARMLD=GENERAL EAR MOLD. Visual rating (1 to 9 score) where a “1” isvery susceptible and a “9” is very resistant. This is based on overallrating for ear mold of mature ears without determining the specific moldorganism, and may not be predictive for a specific ear mold.

EARSZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher therating the larger the ear size.

EBTSTK=EARLY BRITTLE STALK. A count of the number of “snapped” plantsper plot following severe winds when the corn plant is experiencing veryrapid vegetative growth in the V5-V8 stage. Expressed as percent ofplants that did not snap.

ECB1 LF=EUROPEAN CORN BORER FIRST GENERATION LEAF FEEDING (Ostrinianubilalis). A 1 to 9 visual rating indicating the resistance topreflowering leaf feeding by first generation European Corn Borer. Ahigher score indicates a higher resistance.

ECB2IT=EUROPEAN CORN BORER SECOND GENERATION INCHES OF TUNNELING(Ostrinia nubilalis). Average inches of tunneling per plant in thestalk.

ECB2SC=EUROPEAN CORN BORER SECOND GENERATION (Ostrinia nubilalis). A 1to 9 visual rating indicating post flowering degree of stalk breakageand other evidence of feeding by European Corn Borer, Second Generation.A higher score indicates a higher resistance.

ECBDPE=EUROPEAN CORN BORER DROPPED EARS (Ostrinia nubilalis). Droppedears due to European Corn Borer. Percentage of plants that did not dropears under second generation corn borer infestation.

EGRWTH=EARLY GROWTH. This is a measure of the relative height and sizeof a corn seedling at the 2-4 leaf stage of growth. This is a visualrating (1 to 9), with 1 being weak or slow growth, 5 being averagegrowth and 9 being strong growth. Taller plants, wider leaves, moregreen mass and darker color constitute higher score.

ELITE INBRED. An inbred that contributed desirable qualities when usedto produce commercial hybrids. An elite inbred may also be used infurther breeding for the purpose of developing further improvedvarieties.

ERTLDG=EARLY ROOT LODGING. Early root lodging is the percentage ofplants that do not root lodge prior to or around anthesis; plants thatlean from the vertical axis at an approximately 30 degree angle orgreater would be counted as root lodged.

ERTLPN=EARLY ROOT LODGING. An estimate of the percentage of plants thatdo not root lodge prior to or around anthesis; plants that lean from thevertical axis at an approximately 30 degree angle or greater would beconsidered as root lodged.

ERTLSC=EARLY ROOT LODGING SCORE. Score for severity of plants that leanfrom a vertical axis at an approximate 30 degree angle or greater whichtypically results from strong winds prior to or around floweringrecorded within 2 weeks of a wind event. Expressed as a 1 to 9 scorewith 9 being no lodging.

ESTCNT=EARLY STAND COUNT. This is a measure of the stand establishmentin the spring and represents the number of plants that emerge on perplot basis for the inbred or hybrid.

EYESPT=EYE SPOT (Kabatiella zeae or Aureobasidium zeae). A 1 to 9 visualrating indicating the resistance to Eye Spot. A higher score indicates ahigher resistance.

FUSERS=FUSARIUM EAR ROT SCORE (Fusarium moniliforme or Fusariumsubglutinans). A 1 to 9 visual rating indicating the resistance toFusarium ear rot. A higher score indicates a higher resistance.

GDU=GROWING DEGREE UNITS. Using the Barger Heat Unit Theory, whichassumes that maize growth occurs in the temperature range 50 degrees F.−86 degrees F. and that temperatures outside this range slow downgrowth; the maximum daily heat unit accumulation is 36 and the minimumdaily heat unit accumulation is 0. The seasonal accumulation of GDU is amajor factor in determining maturity zones.

GDUSHD=GDU TO SHED. The number of growing degree units (GDUs) or heatunits required for an inbred line or hybrid to have approximately 50percent of the plants shedding pollen and is measured from the time ofplanting. Growing degree units are calculated by the Barger Method,where the heat units for a 24-hour period are:${GDU} = {\frac{\left( {{Max}.\quad{temp}.{+ {{Min}.\quad{temp}.}}} \right)}{2} - 50}$

The highest maximum temperature used is 86 degrees F. and the lowestminimum temperature used is 50 degrees F. For each inbred or hybrid ittakes a certain number of GDUs to reach various stages of plantdevelopment.

GDUSLK=GDU TO SILK. The number of growing degree units required for aninbred line or hybrid to have approximately 50 percent of the plantswith silk emergence from time of planting. Growing degree units arecalculated by the Barger Method as given in GDU SHD definition.

GENOTYPE. Refers to the genetic constitution of a cell or organism.

GIBERS=GIBBERELLA EAR ROT (PINK MOLD) (Gibberella zeae). A 1 to 9 visualrating indicating the resistance to Gibberella Ear Rot. A higher scoreindicates a higher resistance.

GIBROT=GIBBERELLA STALK ROT SCORE. Score of stalk rot severity due toGibberella (Gibberella zeae). Expressed as a 1 to 9 score with 9 beinghighly resistant.

GLFSPT=GRAY LEAF SPOT (Cercospora zeae-maydis). A 1 to 9 visual ratingindicating the resistance to Gray Leaf Spot. A higher score indicates ahigher resistance.

GOSWLT=GOSS' WILT (Corynebacterium nebraskense). A 1 to 9 visual ratingindicating the resistance to Goss' Wilt. A higher score indicates ahigher resistance.

GRNAPP=GRAIN APPEARANCE. This is a 1 to 9 rating for the generalappearance of the shelled grain as it is harvested based on such factorsas the color of harvested grain, any mold on the grain, and any crackedgrain. High scores indicate good grain visual quality.

HAPLOID PLANT PART. Refers to a plant part or cell that has the samehaploid genotype as PHCWK.

HCBLT=HELMINTHOSPORIUM CARBONUM LEAF BLIGHT (Helminthosporium carbonum).A 1 to 9 visual rating indicating the resistance to Helminthosporiuminfection. A higher score indicates a higher resistance.

HD SMT=HEAD SMUT (Sphacelotheca reiliana). This score indicates thepercentage of plants not infected.

HSKCVR=HUSK COVER. A 1 to 9 score based on performance relative to keychecks, with a score of 1 indicating very short husks, tip of ear andkernels showing; 5 is intermediate coverage of the ear under mostconditions, sometimes with thin husk; and a 9 has husks extending andclosed beyond the tip of the ear. Scoring can best be done nearphysiological maturity stage or any time during dry down untilharvested.

INC D/A=GROSS INCOME (DOLLARS PER ACRE). Relative income per acreassuming drying costs of two cents per point above 15.5 percent harvestmoisture and current market price per bushel.

INCOME/ACRE. Income advantage of hybrid to be patented over other hybridon per acre basis.

INC ADV=GROSS INCOME ADVANTAGE. GROSS INCOME advantage of variety #1over variety #2.

KSZDCD=KERNEL SIZE DISCARD. The percent of discard seed; calculated asthe sum of discarded tip kernels and extra large kernels.

LINKAGE. Refers to a phenomenon wherein alleles on the same chromosometend to segregate together more often than expected by chance if theirtransmission was independent.

LINKAGE DISEQUILIBRIUM. Refers to a phenomenon wherein alleles tend toremain together in linkage groups when segregating from parents tooffspring, with a greater frequency than expected from their individualfrequencies.

L/POP=YIELD AT LOW DENSITY. Yield ability at relatively low plantdensities on a 1 to 9 relative system with a higher number indicatingthe hybrid responds well to low plant densities for yield relative toother hybrids. A 1, 5, and 9 would represent very poor, average, andvery good yield response, respectively, to low plant density.

LRTLDG=LATE ROOT LODGING. Late root lodging is the percentage of plantsthat do not root lodge after anthesis through harvest; plants that leanfrom the vertical axis at an approximately 30 degree angle or greaterwould be counted as root lodged.

LRTLPN=LATE ROOT LODGING. Late root lodging is an estimate of thepercentage of plants that do not root lodge after anthesis throughharvest; plants that lean from the vertical axis at an approximately 30degree angle or greater would be considered as root lodged.

LRTLSC=LATE ROOT LODGING SCORE. Score for severity of plants that leanfrom a vertical axis at an approximate 30 degree angle or greater whichtypically results from strong winds after flowering. Recorded prior toharvest when a root-lodging event has occurred. This lodging results inplants that are leaned or “lodged” over at the base of the plant and donot straighten or “goose-neck” back to a vertical position. Expressed asa 1 to 9 score with 9 being no lodging.

MDMCPX=MAIZE DWARF MOSAIC COMPLEX (MDMV=Maize Dwarf Mosaic Virus andMCDV=Maize Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating theresistance to Maize Dwarf Mosaic Complex. A higher score indicates ahigher resistance.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture ofthe grain at harvest.

MSTADV=MOISTURE ADVANTAGE. The moisture advantage of variety #1 overvariety #2 as calculated by: MOISTURE of variety #2 −MOISTURE of variety#1 =MOISTURE ADVANTAGE of variety #1.

NLFBLT=NORTHERN LEAF BLIGHT (Helminthosporium turcicum or Exserohilumturcicum). A 1 to 9 visual rating indicating the resistance to NorthernLeaf Blight. A higher score indicates a higher resistance.

OILT=GRAIN OIL. Absolute value of oil content of the kernel as predictedby Near-infrared Transmittance and expressed as a percent of dry matter.

PEDIGREE DISTANCE. Relationship among generations based on theirancestral links as evidenced in pedigrees. May be measured by thedistance of the pedigree from a given starting point in the ancestry.

PERCENT IDENTITY. Percent identity as used herein refers to thecomparison of the homozygous alleles of two inbred lines. Each inbredplant will have the same allele (and therefore be homozygous) at almostall of their loci. Percent identity is determined by comparing astatistically significant number of the homozygous alleles of two inbredlines. For example, a percent identity of 90% between inbred PHCWK andother inbred line means that the two inbred lines have the same alleleat 90% of their loci.

PERCENT SIMILARITY. Percent similarity as used herein refers to thecomparison of the homozygous alleles of an inbred line with anotherplant. The homozygous alleles of PHCWK are compared with the alleles ofa non-inbred plant, such as a hybrid, and if the allele of the inbredmatches at least one of the alleles from the hybrid then they are scoredas similar. Percent similarity is determined by comparing astatistically significant number of loci and recording the number ofloci with similar alleles as a percentage. For example, a percentsimilarity of 90% between inbred PHCWK and a hybrid maize plant meansthat the inbred line matches at least one of the hybrid alleles at 90%of the loci. In the case of a hybrid produced from PHCWK as the male orfemale parent, such hybrid will comprise two sets of alleles, one set ofwhich will comprise the same alleles as the homozygous alleles of inbredline PHCWK.

PLANT. As used herein, the term “plant” includes reference to animmature or mature whole plant, including a plant that has beendetasseled or from which seed or grain has been removed. Seed or embryothat will produce the plant is also considered to be the plant.

PLANT PARTS. As used herein, the term “plant parts” includes leaves,stems, roots, seed, grain, embryo, pollen, ovules, flowers, ears, cobs,husks, stalks, root tips, anthers, pericarp, silk, tissue, cells and thelike.

PLTHT=PLANT HEIGHT. This is a measure of the height of the plant fromthe ground to the tip of the tassel in centimeters.

POLSC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount ofpollen shed. The higher the score the more pollen shed.

POLWT=POLLEN WEIGHT. This is calculated by dry weight of tasselscollected as shedding commences minus dry weight from similar tasselsharvested after shedding is complete.

POP K/A=PLANT POPULATIONS. Measured as 1000s per acre.

POP ADV=PLANT POPULATION ADVANTAGE. The plant population advantage ofvariety #1 over variety #2 as calculated by PLANT POPULATION of variety#2−PLANT POPULATION of variety #1=PLANT POPULATION ADVANTAGE of variety#1.

PRM=PREDICTED RELATIVE MATURITY. This trait, predicted relativematurity, is based on the harvest moisture of the grain. The relativematurity rating is based on a known set of checks and utilizes standardlinear regression analyses and is also referred to as the ComparativeRelative Maturity Rating System that is similar to the MinnesotaRelative Maturity Rating System.

PRMSHD=A relative measure of the growing degree units (GDU) required toreach 50% pollen shed. Relative values are predicted values from thelinear regression of observed GDU's on relative maturity of commercialchecks.

PROT=GRAIN PROTEIN. Absolute value of protein content of the kernel aspredicted by Near-Infrared Transmittance and expressed as a percent ofdry matter.

RTLDG=ROOT LODGING. Root lodging is the percentage of plants that do notroot lodge; plants that lean from the vertical axis at an approximately30 degree angle or greater would be counted as root lodged.

RTLADV=ROOT LODGING ADVANTAGE. The root lodging advantage of variety #1over variety #2.

SCTGRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount ofscatter grain (lack of pollination or kernel abortion) on the ear. Thehigher the score the less scatter grain.

SDGVGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amountof vegetative growth after emergence at the seedling stage(approximately five leaves). A higher score indicates better vigor.

SEL IND=SELECTION INDEX. The selection index gives a single measure ofthe hybrid's worth based on information for up to five traits. A maizebreeder may utilize his or her own set of traits for the selectionindex. One of the traits that is almost always included is yield. Theselection index data presented in the tables represent the mean valueaveraged across testing stations.

SELF POLLINATION. A plant is self-pollinated if pollen from one floweris transferred to the same or another flower of the same plant.

SIB POLLINATION. A plant is sib-pollinated when individuals within thesame family or line are used for pollination.

SLFBLT=SOUTHERN LEAF BLIGHT (Helminthosporium maydis or Bipoladsmaydis). A 1 to 9 visual rating indicating the resistance to SouthernLeaf Blight. A higher score indicates a higher resistance.

SOURST=SOUTHERN RUST (Puccinia polysora). A 1 to 9 visual ratingindicating the resistance to Southern Rust. A higher score indicates ahigher resistance.

STAGRN=STAY GREEN. Stay green is the measure of plant health near thetime of black layer formation (physiological maturity). A high scoreindicates better late-season plant health.

STDADV=STALK STANDING ADVANTAGE. The advantage of variety #1 overvariety #2 for the trait STK CNT.

STKCNT=NUMBER OF PLANTS. This is the final stand or number of plants perplot.

STKLDG=STALK LODGING REGULAR. This is the percentage of plants that didnot stalk lodge (stalk breakage) at regular harvest (when grain moistureis between about 20 and 30%) as measured by either natural lodging orpushing the stalks and determining the percentage of plants that breakbelow the ear.

STKLDL=LATE STALK LODGING. This is the percentage of plants that did notstalk lodge (stalk breakage) at or around late season harvest (whengrain moisture is between about 15 and 18%) as measured by eithernatural lodging or pushing the stalks and determining the percentage ofplants that break below the ear.

STKLDS=STALK LODGING SCORE. A plant is considered as stalk lodged if thestalk is broken or crimped between the ear and the ground. This can becaused by any or a combination of the following: strong winds late inthe season, disease pressure within the stalks, ECB damage orgenetically weak stalks. This trait should be taken just prior to or atharvest. Expressed on a 1 to 9 scale with 9 being no lodging.

STLLPN=LATE STALK LODGING. This is the percent of plants that did notstalk lodge (stalk breakage or crimping) at or around late seasonharvest (when grain moisture is below 20%) as measured by either naturallodging or pushing the stalks and determining the percentage of plantsthat break or crimp below the ear.

STLPCN=STALK LODGING REGULAR. This is an estimate of the percentage ofplants that did not stalk lodge (stalk breakage) at regular harvest(when grain moisture is between about 20 and 30%) as measured by eithernatural lodging or pushing the stalks and determining the percentage ofplants that break below the ear.

STRT=GRAIN STARCH. Absolute value of starch content of the kernel aspredicted by Near-Infrared Transmittance and expressed as a percent ofdry matter.

STWWLT=Stewart's Wilt (Erwinia stewartil). A 1 to 9 visual ratingindicating the resistance to Stewart's Wilt. A higher score indicates ahigher resistance.

TASBLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure thedegree of blasting (necrosis due to heat stress) of the tassel at thetime of flowering. A 1 would indicate a very high level of blasting attime of flowering, while a 9 would have no tassel blasting.

TASSZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate therelative size of the tassel. The higher the rating the larger thetassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams)just prior to pollen shed.

TEXEAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate therelative hardness (smoothness of crown) of mature grain. A 1 would bevery soft (extreme dent) while a 9 would be very hard (flinty or verysmooth crown).

TILLER=TILLERS. A count of the number of tillers per plot that couldpossibly shed pollen was taken. Data are given as a percentage oftillers: number of tillers per plot divided by number of plants perplot.

TSTWT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grainin pounds for a given volume (bushel).

TSWADV=TEST WEIGHT ADVANTAGE. The test weight advantage of variety #1over variety #2.

WIN M %=PERCENT MOISTURE WINS.

WIN Y %=PERCENT YIELD WINS.

YIELD BU/A=YIELD (BUSHELS/ACRE). Yield of the grain at harvest inbushels per acre adjusted to 15% moisture.

YLDADV=YIELD ADVANTAGE. The yield advantage of variety #1 over variety#2 as calculated by: YIELD of variety #1−YIELD variety #2 =yieldadvantage of variety #1.

YLDSC=YIELD SCORE. A 1 to 9 visual rating was used to give a relativerating for yield based on plot ear piles. The higher the rating thegreater visual yield appearance.

Definitions for Area of Adaptability

When referring to area of adaptability, such term is used to describethe location with the environmental conditions that would be well suitedfor this maize line. Area of adaptability is based on a number offactors, for example: days to maturity, insect resistance, diseaseresistance, and drought resistance. Area of adaptability does notindicate that the maize line will grow in every location within the areaof adaptability or that it will not grow outside the area.

-   -   Central Corn Belt: Iowa, Illinois, Indiana    -   Drylands: non-irrigated areas of North Dakota, South Dakota,        Nebraska, Kansas, Colorado and Oklahoma    -   Eastern U.S.: Ohio, Pennsylvania, Delaware, Maryland, Virginia,        and West Virginia    -   North central U.S.: Minnesota and Wisconsin    -   Northeast: Michigan, New York, Vermont, and Ontario and Quebec        Canada    -   Northwest U.S.: North Dakota, South Dakota, Wyoming, Washington,        Oregon, Montana, Utah, and Idaho    -   South central U.S.: Missouri, Tennessee, Kentucky, Arkansas    -   Southeast U.S.: North Carolina, South Carolina, Georgia,        Florida, Alabama, Mississippi, and Louisiana    -   Southwest U.S.: Texas, Oklahoma, New Mexico, Arizona    -   Western U.S.: Nebraska, Kansas, Colorado, and California    -   Maritime Europe: Northern France, Germany, Belgium, Netherlands        and Austria

DETAILED DESCRIPTION OF THE INVENTION AND FURTHER EMBODIMENTS

All tables discussed in the Detailed Description of the Invention andFurther Embodiments section can found at the end of the section.

Morphological and Physiological Characteristics of PHCWK

Inbred maize line PHCWK is a yellow, dent maize inbred with some flintcharacteristics that may be used as either a male or female in theproduction of the first generation F1 maize hybrids although PHCWK maybe best suited for use as a female. Inbred maize line PHCWK is bestadapted to the Northwest, Northcentral and Northeastern United Statesand Canada, and can be used to produce hybrids with approximately 91maturity based on the Comparative Relative Maturity Rating System forharvest moisture of grain. Inbred maize line PHCWK demonstratesexcellent general combining ability for yield, excellent roots, earlyflowering and high test weight as an inbred per se. In hybridcombination, inbred PHCWK demonstrates very high yielding, earlyflowering and fast drydown, excellent roots, test weight and brittlesnap tolerance.

The inbred has shown uniformity and stability within the limits ofenvironmental influence for all the traits as described in the VarietyDescription Information (Table 1, found at the end of the section). Theinbred has been self-pollinated and ear-rowed a sufficient number ofgenerations with careful attention paid to uniformity of plant type toensure the homozygosity and phenotypic stability necessary for use incommercial hybrid seed production. The line has been increased both byhand and in isolated fields with continued observation for uniformity.No variant traits have been observed or are expected in PHCWK.

Inbred maize line PHCWK, being substantially homozygous, can bereproduced by planting seeds of the line, growing the resulting maizeplants under self-pollinating or sib-pollinating conditions withadequate isolation, and harvesting the resulting seed using techniquesfamiliar to the agricultural arts.

Genotypic Characteristics of PHCWK

In addition to phenotypic observations, a plant can also be identifiedby its genotype. The genotype of a plant can be characterized through agenetic marker profile, which can identify plants of the same variety ora related variety, or be used to determine or validate a pedigree. TheSSR profile of Inbred PHCWK can be found in Table 2 at the end of thissection.

As a result of inbreeding, PHCWK is substantially homozygous. Thishomozygosity has been characterized at the loci shown in the markerprofile provided herein. An F1 hybrid made with PHCWK would comprise themarker profile of PHCWK shown herein. This is because an F1 hybrid isthe sum of its inbred parents, e.g., if one inbred parent is homozygousfor allele x at a particular locus, and the other inbred parent ishomozygous for allele y at that locus, the F1 hybrid will be x.y(heterozygous) at that locus. The profile can therefore be used toidentify hybrids comprising PHCWK as a parent, since such hybrids willcomprise two sets of alleles, one set of which will be from PHCWK. Thedetermination of the male set of alleles and the female set of allelesmay be made by profiling the hybrid and the pericarp of the hybrid seed,which is composed of maternal parent cells. The paternal parent profileis obtained by subtracting the pericarp profile from the hybrid profile.

Subsequent generations of progeny produced by selection and breeding areexpected to be of genotype x (homozygous), y (homozygous), or x.y(heterozygous) for these locus positions. When the F1 plant is used toproduce an inbred, the resulting inbred should be either x or y for thatallele. In that regard, a unique allele or combination of alleles uniqueto that inbred can be used to identify progeny plants that retain thoseunique alleles or combinations of alleles.

Therefore, in accordance with the above, an embodiment of this inventionis a PHCWK progeny maize plant or plant part that is a first generationhybrid maize plant comprising two sets of alleles, wherein one set ofthe alleles is the same as PHCWK at all of the SSR loci listed in Table2. A maize cell wherein one set of the alleles is the same as PHCWK atall of the SSR loci listed in Table 2 is also an embodiment of theinvention. This maize cell may be a part of a hybrid seed produced bycrossing PHCWK with another inbred maize plant.

Genetic marker profiles can be obtained by techniques such asRestriction Fragment Length Polymorphisms (RFLPs), Randomly AmplifiedPolymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction(APPCR), DNA Amplification Fingerprinting (DAF), Sequence CharacterizedAmplified Regions (SCARs), Amplified Fragment Length Polymorphisms(AFLPs), Simple Sequence Repeats (SSRs) which are also referred to asMicrosatellites, and Single Nucleotide Polymorphisms (SNPs). Forexample, see Berry, Don, et al., “Assessing Probability of AncestryUsing Simple Sequence Repeat Profiles: Applications to Maize Hybrids andInbreds”, Genetics, 2002, 161:813-824, and Berry, Don, et al.,“Assessing Probability of Ancestry Using Simple Sequence RepeatProfiles: Applications to Maize Inbred Lines and Soybean Varieties”,Genetics, 2003, 165: 331-342, which are incorporated by referenceherein.

Particular markers used for these purposes are not limited to the set ofmarkers disclosed herein, but may include any type of marker and markerprofile which provides a means of distinguishing varieties. In additionto being used for identification of Inbred Line PHCWK, a hybrid producedthrough the use of PHCWK, and the identification or verification ofpedigree for progeny plants produced through the use of PHCWK, thegenetic marker profile is also useful in further breeding and indeveloping an introgressed trait conversion of PHCWK.

Means of performing genetic marker profiles using SSR polymorphisms arewell known in the art. SSRs are genetic markers based on polymorphismsin repeated nucleotide sequences, such as microsatellites. A markersystem based on SSRs can be highly informative in linkage analysisrelative to other marker systems in that multiple alleles may bepresent. Another advantage of this type of marker is that, through useof flanking primers, detection of SSRs can be achieved, for example, bythe polymerase chain reaction (PCR), thereby eliminating the need forlabor-intensive Southern hybridization. The PCR detection is done by useof two oligonucleotide primers flanking the polymorphic segment ofrepetitive DNA. Repeated cycles of heat denaturation of the DNA followedby annealing of the primers to their complementary sequences at lowtemperatures, and extension of the annealed primers with DNA polymerase,comprise the major part of the methodology.

Following amplification, markers can be scored by electrophoresis of theamplification products. Scoring of marker genotype is based on the sizeof the amplified fragment, which may be measured by the base pair weightor molecular weight of the fragment. While variation in the primer usedor in laboratory procedures can affect the reported fragment size,relative values should remain constant regardless of the specific primeror laboratory used. When comparing lines it is preferable if all SSRprofiles are performed in the same lab. The SSR analyses reported hereinwere conducted in-house at Pioneer Hi-Bred. An SSR service is availableto the public on a contractual basis by DNA Landmarks inSaint-Jean-sur-Richelieu, Quebec, Canada (formerly Paragen, CeleraAgGen, Perkin-Elmer AgGen, Linkage Genetics and NPI).

Primers used for the SSRs reported herein are publicly available and maybe found in the Maize GDB on the World Wide Web at maizegdb.org(sponsored by the USDA Agricultural Research Service), in Sharopova etal. (Plant Mol. Biol. 48(5-6):463-481), Lee et al (Plant Mol. Biol.48(5-6); 453-461), or may be constructed from sequences if reportedherein. Primers may be constructed from publicly available sequenceinformation. Some marker information may also be available from DNALandmarks.

Map information is provided by bin number as reported in the Maize GDBfor the IBM 2 and/or IBM 2 Neighbors maps. The bin number digits to theleft of decimal point represent the chromosome on which such marker islocated, and the digits to the right of the decimal represent thelocation on such chromosome. A bin number.xx designation indicates thatthe bin location on that chromosome is not known. Map positions are alsoavailable on the Maize GDB for a variety of different mappingpopulations.

PHCWK and its plant parts can be identified through molecular markerprofile. An inbred corn plant cell having the SSR genetic marker profileshown in Table 2 is an embodiment of the invention. Such cell may beeither diploid or haploid.

Also encompassed within the scope of the invention are plants and plantparts substantially benefiting from the use of PHCWK in theirdevelopment, such as PHCWK comprising a introgressed trait throughbackcross conversion or transformation, and which may be identified byhaving an SSR molecular marker profile with a high percent identity toPHCWK, such as at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%,89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5% identity.Likewise, percent similarity at these percentages may be used toidentify hybrid and other non-inbred plants produced by the use ofPHCWK.

An embodiment of this invention is an inbred PHCWK progeny maize plantor plant part comprising the same homozygous alleles as the plant orplant part of PHCWK for at least 90% of the SSR loci listed in Table 2.A plant cell comprising the same homozygous alleles as a plant cell ofPHCWK for at least 90% of the SSR loci listed in Table 2 is also anembodiment of this invention. In these specific embodiments, 90% mayalso be replaced by any integer or partial integer percent of 80% orgreater as listed above. One means of producing such a progeny plant,plant part or cell is through the backcrossing and/or transformationmethods described herein.

Similarly, an embodiment of this invention is a PHCWK progeny maizeplant or plant part comprising at least one allele per locus that is thesame allele as the plant or plant part of PHCWK for at least 90% of theSSR loci listed in Table 2. This progeny plant may be a hybrid. Aprogeny or hybrid plant cell wherein at least one allele per locus thatis the same allele as the plant cell PHCWK for at least 90% of the SSRloci listed in Table 2 is also a specific embodiment of this invention.In these specific embodiments, 90% may also be replaced by any integerpercent listed above. One means of producing such a progeny or hybridplant, plant part or cell is through the backcrossing and/ortransformation methods described herein.

In addition, the SSR profile of PHCWK also can be used to identifyessentially derived varieties and other progeny lines developed from theuse of PHCWK, as well as cells and other plant parts thereof. Progenyplants and plant parts produced using PHCWK may be identified by havinga molecular marker profile of at least 25%, 30%, 35%, 40%, 45%, 50%,55%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%,73%, 74%, 75%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%,90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5% geneticcontribution from inbred line PHCWK, as measured by either percentidentity or percent similarity.

Comparing PHCWK To Other lnbreds

A breeder uses various methods to help determine which plants should beselected from segregating populations and ultimately which inbred lineswill be used to develop hybrids for commercialization. In addition toknowledge of the germplasm and plant genetics, a part of the selectionprocess is dependent on experimental design coupled with the use ofstatistical analysis. Experimental design and statistical analysis areused to help determine which plants, which family of plants, and finallywhich inbred lines and hybrid combinations are significantly better ordifferent for one or more traits of interest. Experimental designmethods are used to assess error so that differences between two inbredlines or two hybrid lines can be more accurately evaluated. Statisticalanalysis includes the calculation of mean values, determination of thestatistical significance of the sources of variation, and thecalculation of the appropriate variance components. Either a five or aone percent significance level is customarily used to determine whethera difference that occurs for a given trait is real or due to theenvironment or experimental error. One of ordinary skill in the art ofplant breeding would know how to evaluate the traits of two plantvarieties to determine if there is no significant difference between thetwo traits expressed by those varieties. For example, see Fehr, Walt,Principles of Cultivar Development, p. 261-286 (1987) which isincorporated herein by reference. Mean trait values may be used todetermine whether trait differences are significant. Trait values shouldpreferably be measured on plants grown under the same environmentalconditions, and environmental conditions should be appropriate for thetraits or traits being evaluated. Sufficient selection pressure shouldbe present for optimum measurement of traits of interest such asherbicide, insect or disease resistance. Similarly, an introgressedtrait conversion of PHCWK for resistance, such as herbicide resistance,should not be compared to PHCWK in the presence of the herbicide whencomparing non-resistance related traits such as plant height and yield.

In Table 3, data from traits and characteristics of inbred maize linePHCWK per se are given and compared to other maize inbred lines andhybrids. The following are the results of these comparisons:

The results in Table 3A compare inbred PHCWK to inbred PH5TG. Theresults show inbred PHCWK has significantly higher yield, early growthrate and plant height compared to PH5TG.

The results in Table 3B compare inbred PHCWK to inbred PH1CN. Theresults show inbred PHCWK has a significantly larger plant height and alower number of growing degree units required to achieve 50% pollen shedwhen compared to inbred PH1CN.

The results in Table 3C compare inbred PHCWK to inbred PHAA0. Theresults show inbred PHCWK differs significantly from PHAA0 in a numberof traits including yield, plant height and ear height.

The results in Table 3D compare inbred PHCWK to inbred PH75K. Theresults show inbred PHCWK differs significantly from PH75K in a numberof traits including yield, plant height and ear height.

Development of Maize Hybrids Using PHCWK

A single cross maize hybrid results from the cross of two inbred lines,each of which has a genotype that complements the genotype of the other.The hybrid progeny of the first generation is designated F1. In thedevelopment of commercial hybrids in a maize plant breeding program,only the F1 hybrid plants are sought. F1 hybrids are more vigorous thantheir inbred parents. This hybrid vigor, or heterosis, can be manifestedin many polygenic traits, including increased vegetative growth andincreased yield.

PHCWK may be used to produce hybrid maize. One such embodiment is themethod of crossing inbred maize line PHCWK with another maize plant,such as a different maize inbred line, to form a first generation F1hybrid seed. The first generation F1 hybrid seed, plant and plant partproduced by this method is an embodiment of the invention. The firstgeneration F1 seed, plant and plant part will comprise an essentiallycomplete set of the alleles of inbred line PHCWK. One of ordinary skillin the art can utilize either breeder books or molecular methods toidentify a particular F1 hybrid plant produced using inbred line PHCWK.Further, one of ordinary skill in the art may also produce F1 hybridswith transgenic, male sterile and/or backcross conversions of inbredline PHCWK.

The development of a maize hybrid in a maize plant breeding programinvolves three steps: (1) the selection of plants from various germplasmpools for initial breeding crosses; (2) the selfing of the selectedplants from the breeding crosses for several generations to produce aseries of inbred lines, such as PHCWK, which, although different fromeach other, breed true and are highly uniform; and (3) crossing theselected inbred lines with different inbred lines to produce thehybrids. During the inbreeding process in maize, the vigor of the linesdecreases, and so one would not be likely to use PHCWK directly toproduce grain. However, vigor is restored when PHCWK is crossed to adifferent inbred line to produce a commercial F1 hybrid. An importantconsequence of the homozygosity and homogeneity of the inbred line isthat the hybrid between a defined pair of inbreds may be reproducedindefinitely as long as the homogeneity of the inbred parents ismaintained.

PHCWK may be used to produce a single cross hybrid, a three-way hybridor a double cross hybrid. A single cross hybrid is produced when twoinbred lines are crossed to produce the F1 progeny. A double crosshybrid is produced from four inbred lines crossed in pairs (A×B and C×D)and then the two F1 hybrids are crossed again (A×B)×(C×D). A three-waycross hybrid is produced from three inbred lines where two of the inbredlines are crossed (A×B) and then the resulting F1 hybrid is crossed withthe third inbred (A×B)×C. In each case, pericarp tissue from the femaleparent will be a part of and protect the hybrid seed.

Combining Ability of PHCWK

Combining ability of a line, as well as the performance of the line perse, is a factor in the selection of improved maize inbreds. Combiningability refers to a line's contribution as a parent when crossed withother lines to form hybrids. The hybrids formed for the purpose ofselecting superior lines may be referred to as test crosses, and includecomparisons to other hybrid varieties grown in the same environment(same cross, location and time of planting). One way of measuringcombining ability is by using values based in part on the overall meanof a number of test crosses weighted by number of experiment andlocation combinations in which the hybrid combinations occurs. The meanmay be adjusted to remove environmental effects and known geneticrelationships among the lines.

General combining ability provides an overall score for the inbred overa large number of test crosses. Specific combining ability providesinformation on hybrid combinations formed by PHCWK and a specific inbredparent. A line such as PHCWK which exhibits good general combiningability may be used in a large number of hybrid combinations.

A general combining ability report for inbred PHCWK is provided in Table4. This data represents the overall mean value for these traits overhundreds of test crosses. Table 4 demonstrates that inbred PHCWK showsgood general combining ability for hybrid production.

Hybrid Comparisons

These hybrid comparisons represent specific hybrid crosses with PHCWKand a comparison of these specific hybrids with other hybrids withfavorable characteristics. These comparisons illustrate the goodspecific combining ability of PHCWK.

The results in Table 5A compare a specific hybrid for which inbred PHCWKis a parent and a second hybrid, 38R92. The results show that the hybridcontaining inbred PHCWK produced significantly different results overmultiple traits including moisture, plant height and ear height.

The results in Table 5B compare a specific hybrid for which inbred PHCWKis a parent and a second hybrid, 38G60. The results show that the hybridcontaining inbred PHCWK produced significantly different results overmultiple traits including test weight, moisture, and number of growingdegree units required to achieve 50% pollen shed.

The results in Table 5C compare a specific hybrid for which inbred PHCWKis a parent and a second hybrid, 38R69. The results show that the hybridcontaining inbred PHCWK produced significantly different results overmultiple traits including plant height, late season health and testweight.

The results in Table 5D compare a specific hybrid for which inbred PHCWKis a parent and a second hybrid, 38R92. The results show that the hybridcontaining inbred PHCWK produced significantly different results overmultiple traits including plant height, moisture and ear height.

The results in Table 5E compare a specific hybrid for which inbred PHCWKis a parent and a second hybrid, 39K40. The results show that the hybridcontaining inbred PHCWK produced significantly different results overmultiple traits including yield and moisture.

The results in Table 5F compare a specific hybrid for which inbred PHCWKis a parent and a second hybrid, 38G60. The results show that the hybridcontaining inbred PHCWK produced numerically different results overmultiple traits including ear height, plant height and number of growingdegree units required to achieve 50% pollen shed.

The results in Table 5G compare a specific hybrid for which inbred PHCWKis a parent and a second hybrid, 38R69. The results show that the hybridcontaining inbred PHCWK produced numerically different results overmultiple traits including plant height, number of growing degree unitsrequired to achieve 50% pollen shed and number of plants per plot.

Introgression of a new locus or trait into PHCWK.

PHCWK represents a new base genetic line into which a new locus or traitmay be introgressed. Direct transformation and backcrossing representtwo important methods that can be used to accomplish such anintrogression. The term backcross conversion and single locus conversionare used interchangeably to designate the product of a backcrossingprogram.

Backcross Conversions of PHCWK

A backcross conversion of PHCWK occurs when DNA sequences are introducedthrough backcrossing (Hallauer et al, 1988), with PHCWK utilized as therecurrent parent. Both naturally occurring and transgenic DNA sequencesmay be introduced through backcrossing techniques. A backcrossconversion may produce a plant with a trait or locus conversion in atleast one or more backcrosses, including at least 2 crosses, at least 3crosses, at least 4 crosses, at least 5 crosses and the like. Molecularmarker assisted breeding or selection may be utilized to reduce thenumber of backcrosses necessary to achieve the backcross conversion. Forexample, see Openshaw, S. J. et al., Marker-assisted Selection inBackcross Breeding. In: Proceedings Symposium of the Analysis ofMolecular Data, August 1994, Crop Science Society of America, Corvallis,Oreg., where it is demonstrated that a backcross conversion can be madein as few as two backcrosses.

The complexity of the backcross conversion method depends on the type oftrait being transferred (single genes or closely linked genes as vs.unlinked genes), the level of expression of the trait, the type ofinheritance (cytoplasmic or nuclear) and the types of parents includedin the cross. It is understood by those of ordinary skill in the artthat for single gene traits that are relatively easy to classify, thebackcross method is effective and relatively easy to manage. (SeeHallauer et al. in Corn and Corn Improvement, Sprague and Dudley, ThirdEd. 1998). Desired traits that may be transferred through backcrossconversion include, but are not limited to, waxy starch, sterility(nuclear and cytoplasmic), fertility restoration, grain color (white),nutritional enhancements, drought tolerance, nitrogen utilization,altered fatty acid profile, increased digestibility, low phytate,industrial enhancements, disease resistance (bacterial, fungal orviral), insect resistance, herbicide resistance and yield enhancements.In addition, an introgression site itself, such as an FRT site, Lox siteor other site specific integration site, may be inserted by backcrossingand utilized for direct insertion of one or more genes of interest intoa specific plant variety. In some embodiments of the invention, thenumber of loci that may be backcrossed into PHCWK is at least 1, 2, 3,4, or 5 and/or no more than 6, 5, 4, 3, or 2. A single loci may containseveral transgenes, such as a transgene for disease resistance that, inthe same expression vector, also contains a transgene for herbicideresistance. The gene for herbicide resistance may be used as aselectable marker and/or as a phenotypic trait. A single locusconversion of site specific integration system allows for theintegration of multiple genes at the converted loci.

The backcross conversion may result from either the transfer of adominant allele or a recessive allele. Selection of progeny containingthe trait of interest is accomplished by direct selection for a traitassociated with a dominant allele. Transgenes transferred viabackcrossing typically function as a dominant single gene trait and arerelatively easy to classify. Selection of progeny for a trait that istransferred via a recessive allele, such as the waxy starchcharacteristic, requires growing and selfing the first backcrossgeneration to determine which plants carry the recessive alleles.Recessive traits may require additional progeny testing in successivebackcross generations to determine the presence of the locus ofinterest. The last backcross generation is usually selfed to give purebreeding progeny for the gene(s) being transferred, although a backcrossconversion with a stably introgressed trait may also be maintained byfurther backcrossing to the recurrent parent with selection for theconverted trait.

Along with selection for the trait of interest, progeny are selected forthe phenotype of the recurrent parent. While occasionally additionalpolynucleotide sequences or genes may be transferred along with thebackcross conversion, the backcross conversion line “fits into the samehybrid combination as the recurrent parent inbred line and contributesthe effect of the additional gene added through the backcross.” Poehlmanet al. (1995, page 334). It has been proposed that in general thereshould be at least four backcrosses when it is important that therecovered lines be essentially identical to the recurrent parent exceptfor the characteristic being transferred (Fehr 1987, Principles ofCultivar Development). However, as noted above, the number ofbackcrosses necessary can be reduced with the use of molecular markers.Other factors, such as a genetically similar donor parent, may alsoreduce the number of backcrosses necessary.

One process for adding or modifying a trait or locus in maize inbredline PHCWK comprises crossing PHCWK plants grown from PHCWK seed withplants of another maize line that comprise the desired trait or locus,selecting F1 progeny plants that comprise the desired trait or locus toproduce selected F1 progeny plants, crossing the selected progeny plantswith the PHCWK plants to produce backcross progeny plants, selecting forbackcross progeny plants that have the desired trait or locus and themorphological characteristics of maize inbred line PHCWK to produceselected backcross progeny plants; and backcrossing to PHCWK three ormore times in succession to produce selected fourth or higher backcrossprogeny plants that comprise said trait or locus. The modified PHCWK maybe further characterized as having the physiological and morphologicalcharacteristics of maize inbred line PHCWK listed in Table 1 asdetermined at the 5% significance level when grown in the sameenvironmental conditions and/or may be characterized by percentsimilarity or identity to PHCWK as determined by SSR markers. The abovemethod may be utilized with fewer backcrosses in appropriate situations,such as when the donor parent is highly related or markers are used inthe selection step. Desired traits that may be used include thosenucleic acids known in the art, some of which are listed herein, thatwill affect traits through nucleic acid expression or inhibition.Desired loci include the introgression of FRT, Lox and other sites forsite specific integration, which may also affect a desired trait if afunctional nucleic acid is inserted at the integration site.

In addition, the above process and other similar processes describedherein may be used to produce F1 hybrid maize seed by adding a step atthe end of the process that comprises crossing PHCWK with theintrogressed trait or locus with a different maize plant and harvestingthe resultant F1 hybrid maize seed.

Male Sterility and Hybrid Seed Production

Hybrid seed production requires elimination or inactivation of pollenproduced by the female inbred parent. Incomplete removal or inactivationof the pollen provides the potential for self-pollination. A reliablemethod of controlling male fertility in plants offers the opportunityfor improved seed production.

PHCWK can be produced in a male-sterile form. There are several ways inwhich a maize plant can be manipulated so that it is male sterile. Theseinclude use of manual or mechanical emasculation (or detasseling), useof one or more genetic factors that confer male sterility, includingcytoplasmic genetic and/or nuclear genetic male sterility, use ofgametocides and the like. A male sterile inbred designated PHCWK mayinclude one or more genetic factors, which result in cytoplasmic geneticand/or nuclear genetic male sterility. All of such embodiments arewithin the scope of the present claims. The male sterility may be eitherpartial or complete male sterility.

Hybrid maize seed is often produced by a male sterility systemincorporating manual or mechanical detasseling. Alternate strips of twomaize inbreds are planted in a field, and the pollen-bearing tassels areremoved from one of the inbreds (female). Provided that there issufficient isolation from sources of foreign maize pollen, the ears ofthe detasseled inbred will be fertilized only from the other inbred(male), and the resulting seed is therefore hybrid and will form hybridplants.

The laborious detasseling process can be avoided by using cytoplasmicmale-sterile (CMS) inbreds. Plants of a CMS inbred are male sterile as aresult of genetic factors in the cytoplasm, as opposed to the nucleus,and so nuclear linked genes are not transferred during backcrossing.Thus, this characteristic is inherited exclusively through the femaleparent in maize plants, since only the female provides cytoplasm to thefertilized seed. CMS plants are fertilized with pollen from anotherinbred that is not male-sterile. Pollen from the second inbred may ormay not contribute genes that make the hybrid plants male-fertile, andeither option may be preferred depending on the intended use of thehybrid. The same hybrid seed, a portion produced from detasseled fertilemaize and a portion produced using the CMS system, can be blended toinsure that adequate pollen loads are available for fertilization whenthe hybrid plants are grown. CMS systems have been successfully usedsince the 1950's, and the male sterility trait is routinely backcrossedinto inbred lines. See Wych, p. 585-586, 1998.

There are several methods of conferring genetic male sterilityavailable, such as multiple mutant genes at separate locations withinthe genome that confer male sterility, as disclosed in U.S. Pat. Nos.4,654,465 and 4,727,219 to Brar et al. and chromosomal translocations asdescribed by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. Inaddition to these methods, Albertsen et al., U.S. Pat. No. 5,432,068,describe a system of nuclear male sterility which includes: identifyinga gene which is critical to male fertility; silencing this native genewhich is critical to male fertility; removing the native promoter fromthe essential male fertility gene and replacing it with an induciblepromoter; inserting this genetically engineered gene back into theplant; and thus creating a plant that is male sterile because theinducible promoter is not “on” resulting in the male fertility gene notbeing transcribed. Fertility is restored by inducing, or turning “on”,the promoter, which in turn allows the gene that confers male fertilityto be transcribed.

These, and the other methods of conferring genetic male sterility in theart, each possess their own benefits and drawbacks. Some other methodsuse a variety of approaches such as delivering into the plant a geneencoding a cytotoxic substance associated with a male tissue specificpromoter or an antisense system in which a gene critical to fertility isidentified and an antisense to that gene is inserted in the plant (see:Fabinjanski, et al. EPO 89/3010153.8 publication no. 329,308 and PCTapplication PCT/CA90/00037 published as WO 90/08828).

Another system for controlling male sterility makes use of gametocides.Gametocides are not a genetic system, but rather a topical applicationof chemicals. These chemicals affect cells that are critical to malefertility. The application of these chemicals affects fertility in theplants only for the growing season in which the gametocide is applied(see Carlson, Glenn R., U.S. Pat. No. 4,936,904). Application of thegametocide, timing of the application and genotype specificity oftenlimit the usefulness of the approach and it is not appropriate in allsituations.

Incomplete control over male fertility may result in self-pollinatedseed being unintentionally harvested and packaged with hybrid seed. Thiswould typically be only female parent seed, because the male plant isgrown in rows that are typically destroyed prior to seed development.Once the seed from the hybrid bag is planted, it is possible to identifyand select these self-pollinated plants. These self-pollinated plantswill be genetically equivalent to one of the inbred lines used toproduce the hybrid. Though the possibility of inbred PHCWK beingincluded in a hybrid seed bag exists, the occurrence is very low becausemuch care is taken by seed companies to avoid such inclusions. It isworth noting that hybrid seed is sold to growers for the production ofgrain or forage and not for breeding or seed production. Theseself-pollinated plants can be identified and selected by one skilled inthe art due to their less vigorous appearance for vegetative and/orreproductive characteristics, including shorter plant height, small earsize, ear and kernel shape, cob color, or other characteristics.

Identification of these self-pollinated lines can also be accomplishedthrough molecular marker analyses. See, “The Identification of FemaleSelfs in Hybrid Maize: A Comparison Using Electrophoresis andMorphology”, Smith, J. S. C. and Wych, R. D., Seed Science andTechnology 14, pp. 1-8 (1995), the disclosure of which is expresslyincorporated herein by reference. Through these technologies, thehomozygosity of the self pollinated line can be verified by analyzingallelic composition at various loci along the genome. Those methodsallow for rapid identification of the invention disclosed herein. Seealso, “Identification of Atypical Plants in Hybrid Maize Seed byPostcontrol and Electrophoresis” Sarca, V. et al., Probleme de GeneticaTeoritica si Aplicata Vol. 20 (1) p. 29-42.

An embodiment of this invention is a process for producing seed ofPHCWK, comprising planting a collection of seed comprising seed of ahybrid, one of whose parents is inbred PHCWK, said collection alsocomprising seed of said inbred, growing plants from said collection ofseed, identifying inbred parent plants, selecting said inbred parentplant; and controlling pollination to preserve the homozygosity of saidinbred parent plant.

Transformation

The advent of new molecular biological techniques has allowed theisolation and characterization of genetic elements with specificfunctions, such as encoding specific protein products. Scientists in thefield of plant biology developed a strong interest in engineering thegenome of plants to contain and express foreign genetic elements, oradditional, or modified versions of native or endogenous geneticelements in order to alter the traits of a plant in a specific manner.Any DNA sequences, whether from a different species or from the samespecies, that are inserted into the genome using transformation arereferred to herein collectively as “transgenes”. In some embodiments ofthe invention, a transformed variant of PHCWK may contain at least onetransgene but could contain at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10and/or no more than 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, or 2.Over the last fifteen to twenty years several methods for producingtransgenic plants have been developed, and the present invention alsorelates to transformed versions of the claimed inbred maize line PHCWKas well as hybrid combinations thereof.

Numerous methods for plant transformation have been developed, includingbiological and physical plant transformation protocols. See, forexample, Miki et al., “Procedures for Introducing Foreign DNA intoPlants” in Methods in Plant Molecular Biology and Biotechnology, Glick,B. R. and Thompson, J. E. Eds. (CRC Press, Inc., Boca Raton, 1993) pages67-88 and Armstrong, “The First Decade of Maize Transformation: A Reviewand Future Perspective” (Maydica 44:101-109, 1999). In addition,expression vectors and in vitro culture methods for plant cell or tissuetransformation and regeneration of plants are available. See, forexample, Gruber et al., “Vectors for Plant Transformation” in Methods inPlant Molecular Biology and Biotechnology, Glick, B. R. and Thompson, J.E. Eds. (CRC Press, Inc., Boca Raton, 1993) pages 89-119.

The most prevalent types of plant transformation involve theconstruction of an expression vector. Such a vector comprises a DNAsequence that contains a gene under the control of or operatively linkedto a regulatory element, for example a promoter. The vector may containone or more genes and one or more regulatory elements.

A genetic trait which has been engineered into the genome of aparticular maize plant using transformation techniques, could be movedinto the genome of another line using traditional breeding techniquesthat are well known in the plant breeding arts. For example, abackcrossing approach is commonly used to move a transgene from atransformed maize plant to an elite inbred line, and the resultingprogeny would then comprise the transgene(s). Also, if an inbred linewas used for the transformation then the transgenic plants could becrossed to a different inbred in order to produce a transgenic hybridmaize plant.

Various genetic elements can be introduced into the plant genome usingtransformation. These elements include, but are not limited to genes;coding sequences; inducible, constitutive, and tissue specificpromoters; enhancing sequences; and signal and targeting sequences. Forexample, see the traits, genes and transformation methods listed in U.S.Pat. No. 6,118,055.

With transgenic plants according to the present invention, a foreignprotein can be produced in commercial quantities. Thus, techniques forthe selection and propagation of transformed plants, which are wellunderstood in the art, yield a plurality of transgenic plants that areharvested in a conventional manner, and a foreign protein then can beextracted from a tissue of interest or from total biomass. Proteinextraction from plant biomass can be accomplished by known methods whichare discussed, for example, by Heney and Orr, Anal. Biochem. 114: 92-6(1981).

A genetic map can be generated, primarily via conventional RestrictionFragment Length Polymorphisms (RFLP), Polymerase Chain Reaction (PCR)analysis, Simple Sequence Repeats (SSR) and Single NucleotidePolymorphisms (SNP) that identifies the approximate chromosomal locationof the integrated DNA molecule. For exemplary methodologies in thisregard, see Glick and Thompson, METHODS IN PLANT MOLECULAR BIOLOGY ANDBIOTECHNOLOGY 269-284 (CRC Press, Boca Raton,1993).

Wang et al. discuss “Large Scale Identification, Mapping and Genotypingof Single-Nucleotide Polymorphisms in the Human Genome”, Science,280:1077-1082, 1998, and similar capabilities are becoming increasinglyavailable for the corn genome. Map information concerning chromosomallocation is useful for proprietary protection of a subject transgenicplant. If unauthorized propagation is undertaken and crosses made withother germplasm, the map of the integration region can be compared tosimilar maps for suspect plants to determine if the latter have a commonparentage with the subject plant. Map comparisons would involvehybridizations, RFLP, PCR, SSR and sequencing, all of which areconventional techniques. SNPs may also be used alone or in combinationwith other techniques.

Likewise, by means of the present invention, plants can be geneticallyengineered to express various phenotypes of agronomic interest. Throughthe transformation of maize the expression of genes can be modulated toenhance disease resistance, insect resistance, herbicide resistance,agronomic, grain quality and other traits. Transformation can also beused to insert DNA sequences which control or help controlmale-sterility. DNA sequences native to maize as well as non-native DNAsequences can be transformed into maize and used to modulate levels ofnative or non-native proteins. Various promoters, targeting sequences,enhancing sequences, and other DNA sequences can be inserted into themaize genome for the purpose of modulating the expression of proteins.Reduction of the activity of specific genes (also known as genesilencing, or gene suppression) is desirable for several aspects ofgenetic engineering in plants.

Many techniques for gene silencing are well known to one of skill in theart, including but not limited to antisense technology (see, e.g.,Sheehy et al. (1988) PNAS USA 85:8805-8809; and U.S. Pat. Nos.5,107,065; 5,453, 566; and 5,759,829); co-suppression (e.g., Taylor(1997) Plant Cell 9:1245; Jorgensen (1990) Trends Biotech.8(12):340-344; F1avell (1994) PNAS USA 91:3490-3496; Finnegan et al.(1994) Bio/Technology 12: 883-888; and Neuhuber et al. (1994) Mol. Gen.Genet. 244:230-241); RNA interference (Napoli et al. (1990) Plant Cell2:279-289; U.S. Pat. No. 5,034,323; Sharp (1999) Genes Dev. 13:139-141;Zamore et al. (2000) Cell 101:25-33; and Montgomery et al. (1998) PNASUSA 95:15502-15507), virus-induced gene silencing (Burton, et al. (2000)Plant Cell 12:691-705; and Baulcombe (1999) Curr. Op. Plant Bio.2:109-113); target-RNA-specific ribozymes (Haseloff et al. (1988) Nature334: 585-591); hairpin structures (Smith et al. (2000) Nature407:319-320; WO 99/53050; and WO 98/53083); ribozymes (Steinecke et al.((1992) EMBO J. 11:1525; and Perriman et al. ((1993) Antisense Res. Dev.3:253); oligonucleotide mediated targeted modification (e.g., WO03/076574 and WO 99/25853); Zn-finger targeted molecules (e.g., WO01/52620; WO 03/048345; and WO 00/42219); and other methods orcombinations of the above methods known to those of skill in the art.

Exemplary transgenes useful for genetic engineering include, but are notlimited to, those categorized below.

1. Transgenes That Confer Resistance To Pests or Disease And ThatEncode:

(A) Plant disease resistance genes. Plant defenses are often activatedby specific interaction between the product of a disease resistance gene(R) in the plant and the product of a corresponding avirulence (Avr)gene in the pathogen. A plant variety can be transformed with clonedresistance gene to engineer plants that are resistant to specificpathogen strains. See, for example Jones et al., Science 266: 789 (1994)(cloning of the tomato Cf-9 gene for resistance to Cladosporium fulvum);Martin et al., Science 262: 1432 (1993) (tomato Pto gene for resistanceto Pseudomonas syringae pv. tomato encodes a protein kinase); Mindrinoset al., Cell 78: 1089 (1994) (Arabidopsis RSP2 gene for resistance toPseudomonas syringae). A plant resistant to a disease is one that ismore resistant to a pathogen as compared to the wild type plant.

(B) A Bacillus thuringiensis protein, a derivative thereof or asynthetic polypeptide modeled thereon. See, for example, Geiser et al.,Gene 48: 109 (1986), who disclose the cloning and nucleotide sequence ofa Bt delta-endotoxin gene. Moreover, DNA molecules encodingdelta-endotoxin genes can be purchased from American Type CultureCollection (Rockville, Md.), for example, under ATCC Accession Nos.40098, 67136, 31995 and 31998. Other examples of Bacillus thuringiensistransgenes being genetically engineered are given in the followingpatents and patent applications and hereby are incorporated by referencefor this purpose: U.S. Pat. Nos. 5,188,960; 5,689,052; 5,880,275; WO91/114778; WO 99/31248; WO 01/12731; WO 99/24581; WO 97/40162 and U.S.application Ser. Nos. 10/032,717; 10/414,637; and 10/606,320.

(C) An insect-specific hormone or pheromone such as an ecdysteroid andjuvenile hormone, a variant thereof, a mimetic based thereon, or anantagonist or agonist thereof. See, for example, the disclosure byHammock et al., Nature 344: 458 (1990), of baculovirus expression ofcloned juvenile hormone esterase, an inactivator of juvenile hormone.

(D) An insect-specific peptide which, upon expression, disrupts thephysiology of the affected pest. For example, see the disclosures ofRegan, J. Biol. Chem. 269: 9 (1994) (expression cloning yields DNAcoding for insect diuretic hormone receptor), and Pratt et al., Biochem.Biophys. Res. Comm.163: 1243 (1989) (an allostatin is identified inDiploptera puntata). See also U.S. Pat. No.5,266,317 to Tomalski et al.,who disclose genes encoding insect-specific toxins.

(E) An enzyme responsible for an hyperaccumulation of a monterpene, asesquiterpene, a steroid, hydroxamic acid, a phenylpropanoid derivativeor another non-protein molecule with insecticidal activity.

(F) An enzyme involved in the modification, including thepost-translational modification, of a biologically active molecule; forexample, a glycolytic enzyme, a proteolytic enzyme, a lipolytic enzyme,a nuclease, a cyclase, a transaminase, an esterase, a hydrolase, aphosphatase, a kinase, a phosphorylase, a polymerase, an elastase, achitinase and a glucanase, whether natural or synthetic. See PCTapplication WO 93/02197 in the name of Scott et al., which discloses thenucleotide sequence of a callase gene. DNA molecules which containchitinase-encoding sequences can be obtained, for example, from the ATCCunder Accession Nos. 39637 and 67152. See also Kramer et al., InsectBiochem. Molec. Biol.23: 691 (1993), who teach the nucleotide sequenceof a cDNA encoding tobacco hookworm chitinase, and Kawalleck et al.,Plant Molec. Biol. 21: 673 (1993), who provide the nucleotide sequenceof the parsley ubi4-2 polyubiquitin gene.

(G) A molecule that stimulates signal transduction. For example, see thedisclosure by Botella et al., Plant Molec. Biol. 24: 757 (1994), ofnucleotide sequences for mung bean calmodulin cDNA clones, and Griess etal., Plant Physiol. 104: 1467 (1994), who provide the nucleotidesequence of a maize calmodulin cDNA clone.

(H) A hydrophobic moment peptide. See PCT application WO 95/16776(disclosure of peptide derivatives of Tachyplesin which inhibit fungalplant pathogens) and PCT application WO 95/18855 (teaches syntheticantimicrobial peptides that confer disease resistance), the respectivecontents of which are hereby incorporated by reference for this purpose.

(I) A membrane permease, a channel former or a channel blocker. Forexample see the disclosure by Jaynes et al., Plant Sci. 89: 43 (1993),of heterologous expression of a cecropin-beta lytic peptide analog torender transgenic tobacco plants resistant to Pseudomonas solanacearum.

(J) A viral-invasive protein or a complex toxin derived therefrom. Forexample, the accumulation of viral coat proteins in transformed plantcells imparts resistance to viral infection and/or disease developmenteffected by the virus from which the coat protein gene is derived, aswell as by related viruses. See Beachy et al., Ann. Rev. Phytopathol.28:451 (1990). Coat protein-mediated resistance has been conferred upontransformed plants against alfalfa mosaic virus, cucumber mosaic virus,tobacco streak virus, potato virus X, potato virus Y, tobacco etchvirus, tobacco rattle virus and tobacco mosaic virus. Id.

(K) An insect-specific antibody or an immunotoxin derived therefrom.Thus, an antibody targeted to a critical metabolic function in theinsect gut would inactivate an affected enzyme, killing the insect. Cf.Taylor et al., Abstract #497, SEVENTH INT'L SYMPOSIUM ON MOLECULARPLANT-MICROBE INTERACTIONS (Edinburgh, Scotland, 1994) (enzymaticinactivation in transgenic tobacco via production of single-chainantibody fragments).

(L) A virus-specific antibody. See, for example, Tavladoraki et al.,Nature 366: 469 (1993), who show that transgenic plants expressingrecombinant antibody genes are protected from virus attack.

(M) A developmental-arrestive protein produced in nature by a pathogenor a parasite. Thus, fungal endo alpha-1,4-D-polygalacturonasesfacilitate fungal colonization and plant nutrient release bysolubilizing plant cell wall homo-alpha-1,4-D-galacturonase. See Lamb etal., Bio/Technology 10: 1436 (1992). The cloning and characterization ofa gene which encodes a bean endopolygalacturonase-inhibiting protein isdescribed by Toubart et al., Plant J. 2: 367 (1992).

(N) A developmental-arrestive protein produced in nature by a plant. Forexample, Logemann et al., Bio/Technology 10: 305 (1992), have shown thattransgenic plants expressing the barley ribosome-inactivating gene havean increased resistance to fungal disease.

(O) Genes involved in the Systemic Acquired Resistance (SAR) Responseand/or the pathogenesis related genes. Briggs, S., Current Biology, 5(2)(1995).

(P) Antifungal genes (Cornelissen and Melchers, PI. Physiol.101:709-712, (1993) and Parijs et al., Planta 183:258-264, (1991) andBushnell et al., Can. J. of Plant Path. 20(2):137-149 (1998).

(Q) Detoxification genes, such as for fumonisin, beauvericin,moniliformin and zearalenone and their structurally related derivatives.For example, see U.S. Pat. No. 5,792,931.

(R) Cystatin and cysteine proteinase inhibitors.

(S) Defensin genes. See WO03000863.

(T) Genes conferring resistance to nematodes. See WO 03/033651 and Urwinet. al., Planta 204:472479 (1998).

2. Transgenes That Confer Resistance to a Herbicide, for Example:

(A) A herbicide that inhibits the growing point or meristem, such as animidazolinone or a sulfonylurea. Exemplary genes in this category codefor mutant ALS and AHAS enzyme as described, for example, by Lee et al.,EMBO J. 7: 1241 (1988), and Miki et al., Theor. Appl. Genet. 80:449(1990), respectively. See also, U.S. Pat. Nos. 5,605,011; 5,013,659;5,141,870; 5,767,361; 5,731,180; 5,304,732; 4,761,373; 5,331,107;5,928,937; and 5,378,824; and international publication WO 96/33270,which are incorporated herein by reference for this purpose.

(B) Glyphosate (resistance imparted by mutant5-enolpyruvl-3-phosphikimate synthase (EPSP) and aroA genes,respectively) and other phosphono compounds such as glufosinate(phosphinothricin acetyl transferase (PAT) and Streptomyceshygroscopicus phosphinothricin acetyl transferase (bar) genes), andpyridinoxy or phenoxy proprionic acids and cycloshexones (ACCaseinhibitor-encoding genes). See, for example, U.S. Pat. No. 4,940,835 toShah et al., which discloses the nucleotide sequence of a form of EPSPSwhich can confer glyphosate resistance. U.S. Pat. No. 5,627,061 to Barryet al. also describes genes encoding EPSPS enzymes. See also U.S. Pat.Nos. 6,248,876 B1; 6,040,497; 5,804,425; 5,633,435; 5,145,783;4,971,908; 5,312,910; 5,188,642; 4,940,835; 5,866,775; 6,225,114 B1;6,130,366; 5,310,667; 4,535,060; 4,769,061; 5,633,448; 5,510,471; Re.36,449; RE 37,287 E; and 5,491,288; and international publications WO97/04103; WO 97/04114; WO 00/66746; WO 01/66704; WO 00/66747 and WO00/66748, which are incorporated herein by reference for this purpose.Glyphosate resistance is also imparted to plants that express a genethat encodes a glyphosate oxido-reductase enzyme as described more fullyin U.S. Pat. Nos. 5,776,760 and 5,463,175, which are incorporated hereinby reference for this purpose. In addition glyphosate resistance can beimparted to plants by the over expression of genes encoding glyphosateN-acetyltransferase. See, for example, U.S. Application Serial Nos.60/244,385; 60/377,175 and 60/377,719. A DNA molecule encoding a mutantaroA gene can be obtained under ATCC accession No. 39256, and thenucleotide sequence of the mutant gene is disclosed in U.S. Pat. No.4,769,061 to Comai. European patent application No. 0 333 033 to Kumadaet al. and U.S. Pat. No. 4,975,374 to Goodman et al. disclose nucleotidesequences of glutamine synthetase genes which confer resistance toherbicides such as L-phosphinothricin. The nucleotide sequence of aphosphinothricin-acetyl-transferase gene is provided in European PatentNo. 0 242 246 and 0 242 236 to Leemans et al. De Greef et al.,Bio/Technology 7: 61 (1989), describe the production of transgenicplants that express chimeric bar genes coding for phosphinothricinacetyl transferase activity. See also, U.S. Pat. Nos. 5,969,213;5,489,520; 5,550,318; 5,874,265; 5,919,675; 5,561,236; 5,648,477;5,646,024; 6,177,616 B1; and 5,879,903, which are incorporated herein byreference for this purpose. Exemplary genes conferring resistance tophenoxy proprionic acids and cycloshexones, such as sethoxydim andhaloxyfop, are the Acc1-S1, Acc1-S2 and Acc1-S3 genes described byMarshall et al., Theor. Appl. Genet. 83: 435 (1992).

(C) A herbicide that inhibits photosynthesis, such as a triazine (psbAand gs+genes) and a benzonitrile (nitrilase gene). Przibilla et al.,Plant Cell 3: 169 (1991), describe the transformation of Chlamydomonaswith plasmids encoding mutant psbA genes. Nucleotide sequences fornitrilase genes are disclosed in U.S. Pat. No. 4,810,648 to Stalker, andDNA molecules containing these genes are available under ATCC AccessionNos. 53435, 67441 and 67442. Cloning and expression of DNA coding for aglutathione S-transferase is described by Hayes et al., Biochem. J. 285:173 (1992).

(D) Acetohydroxy acid synthase, which has been found to make plants thatexpress this enzyme resistant to multiple types of herbicides, has beenintroduced into a variety of plants (see, e.g., Hattori et al. (1995)Mol Gen Genet 246:419). Other genes that confer tolerance to herbicidesinclude: a gene encoding a chimeric protein of rat cytochrome P4507A1and yeast NADPH-cyctochrome P450 oxidoreductase (Shiota et al. (1994)Plant PhysiolPlant Physiol 106:17), genes for glutathione reductase andsuperoxide dismutase (Aono et al. (1995) Plant Cell Physiol 36:1687, andgenes for various phosphotransferases (Datta et al. (1992) Plant MolBiol 20:619).

(E) Protoporphyrinogen oxidase (protox) is necessary for the productionof chlorophyll, which is necessary for all plant survival. The protoxenzyme serves as the target for a variety of herbicidal compounds. Theseherbicides also inhibit growth of all the different species of plantspresent, causing their total destruction. The development of plantscontaining altered protox activity which are resistant to theseherbicides are described in U.S. Pat. Nos. 6,288,306 B1; 6,282,837 B1;and 5,767,373; and international publication WO 01/12825, which areincorporated herein by reference for this purpose.

3. Transgenes That Confer or Contribute to a Grain Trait, Such As:

(A) Modified fatty acid metabolism, for example, by

-   -   (1) Transforming a plant with an antisense gene of stearoyl-ACP        desaturase to increase stearic acid content of the plant. See        Knultzon et al., Proc. Natl. Acad. Sci. USA 89: 2624 (1992),    -   (2) Elevating oleic acid via FAD-2 gene modification and/or        decreasing linolenic acid via FAD-3 gene modification (see U.S.        Pat. Nos. 6,063,947; 6,323,392; and WO 93/11245),    -   (3) Altering conjugated linolenic or linoleic acid content, such        as in WO 01/12800,    -   (4) Modifying LEC1, AGP, Dek1, Superal1, thioredoxin, and/or a        gamma zein knock out or mutant such as cs27 or TUSC 27. For        example, see WO 02/42424, WO 98/22604, WO 03/011015, U.S. Pat.        No. 6,423,886 and Rivera-Madrid, R. et. al. Proc. Natl. Acad.        Sci. 92:5620-5624 (1995).

(B) Decreased phytate content, for example, by the

-   -   (1) Introduction of a phytase-encoding gene would enhance        breakdown of phytate, adding more free phosphate to the        transformed plant. For example, see Van Hartingsveldt et al.,        Gene 127: 87 (1993), for a disclosure of the nucleotide sequence        of an Aspergillus niger phytase gene.    -   (2) Introduction of a gene that reduces phytate content. In        maize, this, for example, could be accomplished, by cloning and        then re-introducing DNA associated with one or more of the        alleles, such as the LPA alleles, identified in maize mutants        characterized by low levels of phytic acid, such as in Raboy et        al., Maydica 35: 383 (1990) and/or by altering inositol kinase        activity as in WO 02/059324, US2003/000901 1, WO 03/027243,        US2003/0079247 and WO 99/05298.

(C) Modified carbohydrate composition effected, for example, bytransforming plants with a gene coding for an enzyme that alters thebranching pattern of starch. See Shiroza et al., J. Bacteriol. 170: 810(1988) (nucleotide sequence of Streptococcus mutans fructosyltransferasegene), Steinmetz et al., Mol. Gen. Genet 200: 220 (1985) (nucleotidesequence of Bacillus subtilis levansucrase gene), Pen et al.,Bio/Technology 10: 292 (1992) (production of transgenic plants thatexpress Bacillus licheniformis alpha-amylase), Elliot et al., PlantMolec. Biol. 21: 515 (1993) (nucleotide sequences of tomato invertasegenes), Søgaard et al., J. Biol. Chem. 268: 22480 (1993) (site-directedmutagenesis of barley alpha-amylase gene), and Fisher et al., PlantPhysiol. 102: 1045 (1993) (maize endosperm starch branching enzyme II).The fatty acid modification genes mentioned above may also be used toeffect starch content and/or composition through the interrelationshipof the starch and oil pathways.

(D) Altered antioxidant content or composition, such as alteration oftocopherol or tocotrienols. For example, see WO 00/68393 involving themanipulation of antioxidant levels through alteration of a phytl prenyltransferase and WO 03/082899 through alteration of a homogentisategeranyl geranyl transferase.

(E) Improved digestibility and/or starch extraction through modificationof UDP-D-xylose 4-epimerase, Fragile 1 and 2, Ref1, HCHL, C4H, such asin WO 99/10498.

4. Genes that Control Male-sterility

(A) Introduction of a deacetylase gene under the control of atapetum-specific promoter and with the application of the chemicalN-Ac-PPT (WO 01/29237).

(B) Introduction of various stamen-specific promoters (WO 92/13956, WO92/13957).

(C) Introduction of the barnase and the barstar gene (Paul et al. PlantMol. Biol. 19:611-622, 1992).

5. Genes that create a site for site specific DNA integration. Thisincludes the introduction of FRT sites that may be used in the FLP/FRTsystem and/or Lox sites that may be used in the Cre/Loxp system. Forexample, see Lyznik, et al., Site-Specific Recombination for GeneticEngineering in Plants, Plant Cell Rep (2003) 21:925-932 and WO 99/25821,which are hereby incorporated by reference. Other systems that may beused include the Gin recombinase of phage Mu (Maeser et al., 1991), thePin recombinase of E. coli (Enomoto et al., 1983), and the R/RS systemof the pSR1 plasmid (Araki et al., 1992).

6. Genes that affect growth characteristics, such as drought toleranceand nitrogen utilization. For example, see WO 00/73475 where water useefficiency is modulated through alteration of malate.

Using PHCWK to Develop Other Maize Inbreds

Inbred maize lines such as PHCWK are typically developed for use in theproduction of hybrid maize lines. However, inbred lines such as PHCWKalso provide a source of breeding material that may be used to developnew maize inbred lines. Plant breeding techniques known in the art andused in a maize plant breeding program include, but are not limited to,recurrent selection, mass selection, bulk selection, mass selection,backcrossing, pedigree breeding, open pollination breeding, restrictionfragment length polymorphism enhanced selection, genetic marker enhancedselection, making double haploids, and transformation. Oftencombinations of these techniques are used. The development of maizehybrids in a maize plant breeding program requires, in general, thedevelopment of homozygous inbred lines, the crossing of these lines, andthe evaluation of the crosses. There are many analytical methodsavailable to evaluate the result of a cross. The oldest and mosttraditional method of analysis is the observation of phenotypic traitsbut genotypic analysis may also be used.

Using PHCWK in a Breeding Program

This invention is directed to methods for producing a maize plant bycrossing a first parent maize plant with a second parent maize plantwherein either the first or second parent maize plant is an inbred maizeplant of the line PHCWK. The other parent may be any other maize plant,such as another inbred line or a plant that is part of a synthetic ornatural population. Any such methods using the inbred maize line PHCWKare part of this invention: selfing, sibbing, backcrosses, massselection, pedigree breeding, bulk selection, hybrid production, crossesto populations, and the like. These methods are well known in the artand some of the more commonly used breeding methods are described below.Descriptions of breeding methods can also be found in one of severalreference books (e.g., Allard, Principles of Plant Breeding, 1960;Simmonds, Principles of Crop Improvement, 1979; Fehr, “Breeding Methodsfor Cultivar Development”, Production and Uses, 2^(nd) ed., Wilcoxeditor, 1987).

Pedigree Breeding

Pedigree breeding starts with the crossing of two genotypes, such asPHCWK and one other elite inbred line having one or more desirablecharacteristics that is lacking or which complements PHCWK. If the twooriginal parents do not provide all the desired characteristics, othersources can be included in the breeding population. In the pedigreemethod, superior plants are selfed and selected in successive filialgenerations. In the succeeding filial generations the heterozygouscondition gives way to homogeneous lines as a result of self-pollinationand selection. Typically in the pedigree method of breeding, five ormore successive filial generations of selfing and selection ispracticed: F1→F2; F2→F3; F3→F4; F4→F5, etc. After a sufficient amount ofinbreeding, successive filial generations will serve to increase seed ofthe developed inbred. Preferably, the inbred line comprises homozygousalleles at about 95% or more of its loci.

In addition to being used to create a backcross conversion, backcrossingcan also be used in combination with pedigree breeding to modify PHCWKand a hybrid that is made using the modified PHCWK. As discussedpreviously, backcrossing can be used to transfer one or morespecifically desirable traits from one line, the donor parent, to aninbred called the recurrent parent, which has overall good agronomiccharacteristics yet lacks that desirable trait or traits. However, thesame procedure can be used to move the progeny toward the genotype ofthe recurrent parent but at the same time retain many components of thenon-recurrent parent by stopping the backcrossing at an early stage andproceeding with selfing and selection. For example, an F1, such as acommercial hybrid, is created. This commercial hybrid may be backcrossedto one of its parent lines to create a BC1 or BC2. Progeny are selfedand selected so that the newly developed inbred has many of theattributes of the recurrent parent and yet several of the desiredattributes of the non-recurrent parent. This approach leverages thevalue and strengths of the recurrent parent for use in new hybrids andbreeding.

Therefore, an embodiment of this invention is a method of making abackcross conversion of maize inbred line PHCWK, comprising the steps ofcrossing a plant of maize inbred line PHCWK with a donor plantcomprising a mutant gene or transgene conferring a desired trait,selecting an F1 progeny plant comprising the mutant gene or transgeneconferring the desired trait, and backcrossing the selected F1 progenyplant to a plant of maize inbred line PHCWK. This method may furthercomprise the step of obtaining a molecular marker profile of maizeinbred line PHCWK and using the molecular marker profile to select for aprogeny plant with the desired trait and the molecular marker profile ofPHCWK. In the same manner, this method may be used to produce an F1hybrid seed by adding a final step of crossing the desired traitconversion of maize inbred line PHCWK with a different maize plant tomake F1 hybrid maize seed comprising a mutant gene or transgeneconferring the desired trait.

Recurrent Selection and Mass Selection

Recurrent selection is a method used in a plant breeding program toimprove a population of plants. PHCWK is suitable for use in a recurrentselection program. The method entails individual plants crosspollinating with each other to form progeny. The progeny are grown andthe superior progeny selected by any number of selection methods, whichinclude individual plant, half-sib progeny, full-sib progeny, selfedprogeny and topcrossing. The selected progeny are cross pollinated witheach other to form progeny for another population. This population isplanted and again superior plants are selected to cross pollinate witheach other. Recurrent selection is a cyclical process and therefore canbe repeated as many times as desired. The objective of recurrentselection is to improve the traits of a population. The improvedpopulation can then be used as a source of breeding material to obtaininbred lines to be used in hybrids or used as parents for a syntheticcultivar. A synthetic cultivar is the resultant progeny formed by theintercrossing of several selected inbreds.

Mass selection is a useful technique when used in conjunction withmolecular marker enhanced selection. In mass selection seeds fromindividuals are selected based on phenotype and/or genotype. Theseselected seeds are then bulked and used to grow the next generation.Bulk selection requires growing a population of plants in a bulk plot,allowing the plants to self-pollinate, harvesting the seed in bulk andthen using a sample of the seed harvested in bulk to plant the nextgeneration. Instead of self pollination, directed pollination could beused as part of the breeding program.

Mutation Breeding

Mutation breeding is one of many methods that could be used to introducenew traits into PHCWK. Mutations that occur spontaneously or areartificially induced can be useful sources of variability for a plantbreeder. The goal of artificial mutagenesis is to increase the rate ofmutation for a desired characteristic. Mutation rates can be increasedby many different means including temperature, long-term seed storage,tissue culture conditions, radiation; such as X-rays, Gamma rays (e.g.cobalt 60 or cesium 137), neutrons, (product of nuclear fission byuranium 235 in an atomic reactor), Beta radiation (emitted fromradioisotopes such as phosphorus 32 or carbon 14), or ultravioletradiation (preferably from 2500 to 2900 nm), or chemical mutagens (suchas base analogues (5-bromo-uracil), related compounds (8-ethoxycaffeine), antibiotics (streptonigrin), alkylating agents (sulfurmustards, nitrogen mustards, epoxides, ethylenamines, sulfates,sulfonates, sulfones, lactones), azide, hydroxylamine, nitrous acid, oracridines. Once a desired trait is observed through mutagenesis thetrait may then be incorporated into existing germplasm by traditionalbreeding techniques, such as backcrossing. Details of mutation breedingcan be found in “Principals of Cultivar Development” Fehr, 1993Macmillan Publishing Company the disclosure of which is incorporatedherein by reference. In addition, mutations created in other lines maybe used to produce a backcross conversion of PHCWK that comprises suchmutation.

Breeding with Molecular Markers

Molecular markers, which includes markers identified through the use oftechniques such as Isozyme Electrophoresis, Restriction Fragment LengthPolymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs),Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA AmplificationFingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs),Amplified Fragment Length Polymorphisms (AFLPs), Simple Sequence Repeats(SSRS) and Single Nucleotide Polymorphisms (SNPs), may be used in plantbreeding methods utilizing PHCWK.

Isozyme Electrophoresis and RFLPs as discussed in Lee, M., “Inbred Linesof Maize and Their Molecular Markers,” The Maize Handbook,(Springer-Verlag, New York, Inc. 1994, at 423-432), have been widelyused to determine genetic composition. Isozyme Electrophoresis has arelatively low number of available markers and a low number of allelicvariants among maize inbreds. RFLPs allow more discrimination becausethey have a higher degree of allelic variation in maize and a largernumber of markers can be found. Both of these methods have been eclipsedby SSRs as discussed in Smith et al., “An evaluation of the utility ofSSR loci as molecular markers in maize (Zea mays L.): comparisons withdata from RFLPs and pedigree”, Theoretical and Applied Genetics (1997)vol. 95 at 163-173 and by Pejic et al., “Comparative analysis of geneticsimilarity among maize inbreds detected by RFLPs, RAPDs, SSRs, andAFLPs,” Theoretical and Applied Genetics (1998) at 1248-1255incorporated herein by reference. SSR technology is more efficient andpractical to use than RFLPs; more marker loci can be routinely used andmore alleles per marker locus can be found using SSRs in comparison toRFLPs. Single Nucleotide Polymorphisms may also be used to identify theunique genetic composition of the invention and progeny lines retainingthat unique genetic composition. Various molecular marker techniques maybe used in combination to enhance overall resolution.

Maize DNA molecular marker linkage maps have been rapidly constructedand widely implemented in genetic studies. One such study is describedin Boppenmaier, et al., “Comparisons among strains of inbreds forRFLPs”, Maize Genetics Cooperative Newsletter, 65:1991, pg. 90, isincorporated herein by reference.

One use of molecular markers is Quantitative Trait Loci (QTL) mapping.QTL mapping is the use of markers, which are known to be closely linkedto alleles that have measurable effects on a quantitative trait.Selection in the breeding process is based upon the accumulation ofmarkers linked to the positive effecting alleles and/or the eliminationof the markers linked to the negative effecting alleles from the plant'sgenome.

Molecular markers can also be used during the breeding process for theselection of qualitative traits. For example, markers closely linked toalleles or markers containing sequences within the actual alleles ofinterest can be used to select plants that contain the alleles ofinterest during a backcrossing breeding program. The markers can also beused to select for the genome of the recurrent parent and against thegenome of the donor parent. Using this procedure can minimize the amountof genome from the donor parent that remains in the selected plants. Itcan also be used to reduce the number of crosses back to the recurrentparent needed in a backcrossing program. The use of molecular markers inthe selection process is often called genetic marker enhanced selection.

Production of Double Haploids

The production of double haploids can also be used for the developmentof inbreds in the breeding program. For example, an F1 hybrid for whichPHCWK is a parent can be used to produce double haploid plants. Doublehaploids are produced by the doubling of a set of chromosomes (1N) froma heterozygous plant to produce a completely homozygous individual. Forexample, see Wan et al., “Efficient Production of Doubled Haploid PlantsThrough Colchicine Treatment of Anther-Derived Maize Callus”,Theoretical and Applied Genetics, 77:889-892, 1989 and US2003/0005479.This can be advantageous because the process omits the generations ofselfing needed to obtain a homozygous plant from a heterozygous source.

Thus, an embodiment of this invention is a process for making asubstantially homozygous PHCWK progeny plant by producing or obtaining aseed from the cross of PHCWK and another maize plant and applying doublehaploid methods to the F1 seed or F1 plant or to any successive filialgeneration. Such methods decrease the number of generations required toproduce an inbred with similar genetics or characteristics to PHCWK. SeeBernardo, R. and Kahler, A. L., Theor. Appl. Genet. 102:986-992, 2001.

In particular, a process of making seed retaining the molecular markerprofile of maize inbred line PHCWK is contemplated, such processcomprising obtaining or producing F1 hybrid seed for which maize inbredline PHCWK is a parent, inducing doubled haploids to create progenywithout the occurrence of meiotic segregation, obtaining the molecularmarker profile of maize inbred line PHCWK, and selecting progeny thatretain the molecular marker profile of PHCWK.

Use Of PHCWK In Tissue Culture

This invention is also directed to the use of PHCWK in tissue culture.As used herein, the term “tissue culture” includes plant protoplasts,plant cell tissue culture, cultured microspores, plant calli, plantclumps, and the like. As used herein, phrases such as “growing the seed”or “grown from the seed” include embryo rescue, isolation of cells fromseed for use in tissue culture, as well as traditional growing methods.

Duncan, Williams, Zehr, and Widholm, Planta (1985) 165:322-332 reflectsthat 97% of the plants cultured that produced callus were capable ofplant regeneration. Subsequent experiments with both inbreds and hybridsproduced 91% regenerable callus that produced plants. In a further studyin 1988, Songstad, Duncan & Widholm in Plant Cell Reports (1988),7:262-265 reports several media additions that enhance regenerability ofcallus of two inbred lines. Other published reports also indicated that“nontraditional” tissues are capable of producing somatic embryogenesisand plant regeneration. K. P. Rao, et al., Maize Genetics CooperationNewsletter, 60:64-65 (1986), refers to somatic embryogenesis from glumecallus cultures and B.V. Conger, et al., Plant Cell Reports, 6:345-347(1987) indicates somatic embryogenesis from the tissue cultures of maizeleaf segments. Thus, it is clear from the literature that the state ofthe art is such that these methods of obtaining plants are, and were,“conventional” in the sense that they are routinely used and have a veryhigh rate of success.

Tissue culture of maize, including tassel/anther culture, is describedin U.S. 2002/0062506A1 and European Patent Application, publication160,390, each of which are incorporated herein by reference for thispurpose. Maize tissue culture procedures are also described in Green andRhodes, “Plant Regeneration in Tissue Culture of Maize,” Maize forBiological Research (Plant Molecular Biology Association,Charlottesville, Va. 1982, at 367-372) and in Duncan, et al., “TheProduction of Callus Capable of Plant Regeneration from Immature Embryosof Numerous Zea Mays Genotypes,” 165 Planta 322-332 (1985). Thus,another aspect of this invention is to provide cells which upon growthand differentiation produce maize plants having the genotype and/orphysiological and morphological characteristics of inbred line PHCWK.

Progeny plants

All plants produced by the use of the methods described herein and thatretain the unique genetic or trait combinations of PHCWK are within thescope of the invention. Progeny of the breeding methods described hereinmay be characterized in any number of ways, such as by traits retainedin the progeny, pedigree and/or molecular markers. Combinations of thesemethods of characterization may be used.

Breeder's of ordinary skill in the art have developed the concept of an“essentially derived variety”, which is defined in 7 U.S.C. § 2104(a)(3)of the Plant Variety Protection Act and is hereby incorporated byreference. Varieties and plants that are essentially derived from PHCWKare within the scope of the invention.

Pedigree is a method used by breeders of ordinary skill in the art todescribe the varieties. Varieties that are more closely related bypedigree are likely to share common genotypes and combinations ofphenotypic characteristics. All breeders of ordinary skill in the artmaintain pedigree records of their breeding programs. These pedigreerecords contain a detailed description of the breeding process,including a listing of all parental lines used in the breeding processand information on how such line was used. One embodiment of thisinvention is progeny plants and parts thereof with at least one ancestorthat is PHCWK, and more specifically, where the pedigree of the progenyincludes 1, 2, 3, 4, and/or 5 or less breeding crosses to a maize plantother than PHCWK or a plant that has PHCWK as a parent or otherprogenitor. A breeder of ordinary skill in the art would know if PHCWKwere used in the development of a progeny line, and would also know howmany crosses to a line other than PHCWK or line with PHCWK as a parentor other progenitor were made in the development of any progeny line.

Molecular markers also provide a means by which those of ordinary skillin the art characterize the similarity or differences of two lines.Using the breeding methods described herein, one can develop individualplants, plant cells, and populations of plants that retain at least 25%,30%, 35%, 40%, 45%, 50%, 55%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%,68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%,82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, 99% or 99.5% genetic contribution from inbred line PHCWK,as measured by either percent identity or percent similarity. Inpedigree analysis the percentage genetic contribution may not beactually known, but on average 50% of the starting germplasm would beexpected to be passed to the progeny line after one cross to anotherline, 25% after another cross to a different line, and so on. Withbackcrossing, the expected contribution of PHCWK after 2, 3, 4 and 5doses (or 1, 2, 3 and 4 backcrosses) would be 75%, 87.5%, 93.75% and96.875% respectively. Actual genetic contribution may be much higherthan the genetic contribution expected by pedigree, especially ifmolecular markers are used in selection. Molecular markers could also beused to confirm and/or determine the pedigree of the progeny line.

Traits are also used by those of ordinary skill in the art tocharacterize progeny. Traits are commonly evaluated at a significancelevel, such as a 1 %, 5% or 10% significance level, when measured inplants grown in the same environmental conditions. For example, abackcross conversion of PHCWK may be characterized as having the samemorphological and physiological traits as PHCWK. The traits used forcomparison may be any or all of the traits shown in Table 1, Table 3,Table 4 or Table 5.

A breeder will commonly work to combine a specific trait of anundeveloped variety of the species, such as a high level of resistanceto a particular disease, with one or more of the elite agronomiccharacteristics (yield, maturity, plant size, lodging resistance, etc.)needed for use as a commercial variety. This combination, oncedeveloped, provides a valuable source of new germplasm for furtherbreeding. For example, it may take 10-15 years and significant effort toproduce such a combination, yet progeny may be developed that retainthis combination in as little as 2-5 years and with much less effort.

Specific Embodiments

Specific methods and products produced using inbred line PHCWK in plantbreeding are discussed in the following sections. The methods outlinedare described in detail by way of illustration and example for purposesof clarity and understanding. However, it will be obvious that certainchanges and modifications may be practiced within the scope of theinvention.

One method for producing a line derived from inbred line PHCWK is asfollows. One of ordinary skill in the art would produce or obtain a seedfrom the cross between inbred line PHCWK and another variety of maize,such as an elite inbred variety. The F1 seed derived from this crosswould be grown to form a homogeneous population. The F1 seed wouldcontain essentially all of the alleles from variety PHCWK andessentially all of the alleles from the other maize variety. The F1nuclear genome would be made-up of 50% variety PHCWK and 50% of theother elite variety. The F1 seed would be grown and allowed to self,thereby forming F2 seed. On average the F2 seed would have derived 50%of its alleles from variety PHCWK and 50% from the other maize variety,but many individual plants from the population would have a greaterpercentage of their alleles derived from PHCWK (Wang J. and R. Bernardo,2000, Crop Sci. 40:659-665 and Bernardo, R. and A. L. Kahler, 2001,Theor. Appi. Genet 102:986-992). The molecular markers of PHCWK could beused to select and retain those lines with high similarity to PHCWK. TheF2 seed would be grown and selection of plants would be made based onvisual observation, markers and/or measurement of traits. The traitsused for selection may be any PHCWK trait described in thisspecification, including the inbred per se maize PHCWK traits describedherein under the detailed description of inbred PHCWK. Such traits mayalso be the good general or specific combining ability of PHCWK,including its ability to produce hybrids with the approximate maturityand/or hybrid combination traits described herein under the detaileddescription of inbred PHCWK. The PHCWK progeny plants that exhibit oneor more of the desired PHCWK traits, such as those listed herein, wouldbe selected and each plant would be harvested separately. This F3 seedfrom each plant would be grown in individual rows and allowed to self.Then selected rows or plants from the rows would be harvestedindividually. The selections would again be based on visual observation,markers and/or measurements for desirable traits of the plants, such asone or more of the desirable PHCWK traits listed herein. The process ofgrowing and selection would be repeated any number of times until aPHCWK progeny inbred plant is obtained. The PHCWK progeny inbred plantwould contain desirable traits derived from inbred plant PHCWK, some ofwhich may not have been expressed by the other maize variety to whichinbred line PHCWK was crossed and some of which may have been expressedby both maize varieties but now would be at a level equal to or greaterthan the level expressed in inbred variety PHCWK. However, in each casethe resulting progeny line would benefit from the efforts of theinventor(s), and would not have existed but for the inventor(s) work increating PHCWK. The PHCWK progeny inbred plants would have, on average,50% of their nuclear genes derived from inbred line PHCWK, but manyindividual plants from the population would have a greater percentage oftheir alleles derived from PHCWK. This breeding cycle, of crossing andselfing, and optional selection, may be repeated to produce anotherpopulation of PHCWK progeny maize plants with, on average, 25% of theirnuclear genes derived from inbred line PHCWK, but, again, manyindividual plants from the population would have a greater percentage oftheir alleles derived from PHCWK. This process can be repeated for athird, fourth, fifth, sixth, seventh or more breeding cycles. Anotherembodiment of the invention is a PHCWK progeny plant that has receivedthe desirable PHCWK traits listed herein through the use of PHCWK, whichtraits were not exhibited by other plants used in the breeding process.

Therefore, an embodiment of this invention is a PHCWK progeny maizeplant, wherein at least one ancestor of said PHCWK progeny maize plantis the maize plant or plant part of PHCWK, and wherein the pedigree ofsaid PHCWK progeny maize plant is within two breeding crosses of PHCWKor a plant that has PHCWK as a parent. The progeny plants, parts andplant cells produced from PHCWK may be further characterized as having apercent marker similarity or identity with PHCWK as described herein.

The previous example can be modified in numerous ways, for instanceselection may or may not occur at every selfing generation, selectionmay occur before or after the actual self-pollination process occurs, orindividual selections may be made by harvesting individual ears, plants,rows or plots at any point during the breeding process described. Doublehaploid breeding methods may be used at any step in the process. Insteadof selfing out of the hybrid produced from the inbred, one could firstcross the hybrid to either a parent line or a different inbred, and thenself out of that cross.

The population of plants produced at each and any cycle of breeding isalso an embodiment of the invention, and on average each such populationwould predictably consist of plants containing approximately 50% of itsgenes from inbred line PHCWK in the first breeding cycle, 25% of itsgenes from inbred line PHCWK in the second breeding cycle, 12.5% of itsgenes from inbred line PHCWK in the third breeding cycle, 6.25% in thefourth breeding cycle, 3.125% in the fifth breeding cycle, and so on.However, in each case the use of PHCWK provides a substantial benefit.The linkage groups of PHCWK would be retained in the progeny lines, andsince current estimates of the maize genome size is about 50,000-80,000genes (Xiaowu, Gai et al., Nucleic Acids Research, 2000, Vol. 28, No. 1,94-96), in addition to non-coding DNA that impacts gene expression, itprovides a significant advantage to use PHCWK as starting material toproduce a line that retains desired genetics or traits of PHCWK.

Therefore, an embodiment of the invention is a process for making apopulation of PHCWK progeny inbred maize plants comprising obtaining orproducing a first generation progeny maize seed comprising the plant ofPHCWK as a parent, growing said first generation progeny maize seed toproduce first generation maize plants and obtaining self or sibpollinated seed from said first generation maize plants, and growing theself or sib pollinated seed to obtain a population of PHCWK progenyinbred maize plants.

The population of PHCWK progeny inbred maize plants produced by thismethod are also embodiments of the invention, and such population as awhole will retain the expected genetic contribution of PHCWK. An inbredline selected from the population of PHCWK progeny inbred maize plantsproduced by this method is an embodiment, and such line may be furthercharacterized by its molecular marker identity or similarity to PHCWK.

In this manner, the invention also encompasses a process for making aPHCWK inbred progeny maize plant comprising the steps of obtaining orproducing a first generation progeny maize seed wherein a parent of saidfirst generation progeny maize seed is a PHCWK plant, growing said firstgeneration progeny maize seed to produce a first generation maize plantand obtaining self or sib pollinated seed from said first generationmaize plant, and producing successive filial generations to obtain aPHCWK inbred progeny maize plant. Also an embodiment of this inventionis the first breeding cycle inbred PHCWK maize plant produced by thismethod.

Crosses to Other Species

The utility of inbred maize line PHCWK also extends to crosses withother species. Commonly, suitable species will be of the familyGraminaceae, and especially of the genera Zea, Tripsacum, Coix,Schlerachne, Polytoca, Chionachne, and Trilobachne, of the tribeMaydeae. Potentially suitable for crosses with PHCWK may be the variousvarieties of grain sorghum, Sorghum bicolor (L.) Moench.

Industrial Applicability

Maize is used as human food, livestock feed, and as raw material inindustry. The food uses of maize, in addition to human consumption ofmaize kernels, include both products of dry- and wet-milling industries.The principal products of maize dry milling are grits, meal and flour.The maize wet-milling industry can provide maize starch, maize syrups,and dextrose for food use. Maize oil is recovered from maize germ, whichis a by-product of both dry- and wet-milling industries.

Maize, including both grain and non-grain portions of the plant, is alsoused extensively as livestock feed, primarily for beef cattle, dairycattle, hogs, and poultry.

Industrial uses of maize include production of ethanol, maize starch inthe wet-milling industry and maize flour in the dry-milling industry.The industrial applications of maize starch and flour are based onfunctional properties, such as viscosity, film formation, adhesiveproperties, and ability to suspend particles. The maize starch and flourhave application in the paper and textile industries. Other industrialuses include applications in adhesives, building materials, foundrybinders, laundry starches, explosives, oil-well muds, and other miningapplications.

Plant parts other than the grain of maize are also used in industry: forexample, stalks and husks are made into paper and wallboard and cobs areused for fuel and to make charcoal.

The seed of inbred maize line PHCWK, the plant produced from the inbredseed, the hybrid maize plant produced from the crossing of the inbred,hybrid seed, and various parts of the hybrid maize plant and transgenicversions of the foregoing, can be utilized for human food, livestockfeed, and as a raw material in industry.

Deposits

Applicant has made a deposit of at least 2500 seeds of Inbred Maize LinePHCWK with the American Type Culture Collection (ATCC), Manassas, Va.20110 USA, ATCC Deposit No. PTA-6350. The seeds deposited with the ATCCon Nov. 30, 2004 were taken from the deposit maintained by PioneerHi-Bred International, Inc., 7100 NW 62^(nd) Avenue, Johnson, Iowa50131-1000 since prior to the filing date of this application. Access tothis deposit will be available during the pendency of the application tothe Commissioner of Patents and Trademarks and persons determined by theCommissioner to be entitled thereto upon request. Upon allowance of anyclaims in the application, the Applicant will make the deposit availableto the public pursuant to 37 C.F.R. § 1.808. This deposit of the InbredMaize Line PHCWK will be maintained in the ATCC depository, which is apublic depository, for a period of 30 years, or 5 years after the mostrecent request, or for the enforceable life of the patent, whichever islonger, and will be replaced if it becomes nonviable during that period.Additionally, Applicant has or will satisfy all of the requirements of37 C.F.R. §§1.801-1.809, including providing an indication of theviability of the sample upon deposit. Applicant has no authority towaive any restrictions imposed by law on the transfer of biologicalmaterial or its transportation in commerce. Applicant does not waive anyinfringement of rights granted under this patent or under the PlantVariety Protection Act (7 USC 2321 et seq.). U.S. Plant VarietyProtection of Inbred Maize Line PHCWK has been applied for. Unauthorizedseed multiplication is prohibited. TABLE 1 VARIETY DESCRIPTIONINFORMATION VARIETY = PHCWK AVG STDEV N 1. TYPE: (Describe intermediatetypes in comments section) 1 = Sweet, 2 = Dent, 3 = Flint, 4 = Flour, 5= Pop and 2 6 = Ornamental. Comments: Flint Like 2. MATURITY: DAYS HEATUNITS Days H. Units Emergence to 50% of plants in silk 52 1,106Emergence to 50% of plants in pollen shed 52 1,098 10% to 90% pollenshed 1 25 50% Silk to harvest at 25% moisture 3. PLANT: Plant Height (totassel tip) (cm) 223.6 29.25 15 Ear Height (to base of top ear node)(cm) 94.5 10.89 15 Length of Top Ear Internode (cm) 14.4 1.72 15 AverageNumber of Tillers per Plant 0.0 0.01 3 Average Number of Ears per Stalk1.1 0.10 3 Anthocyanin of Brace Roots: 1 = Absent, 2 = Faint, 3 3 =Moderate, 4 = Dark 4. LEAF: Width of Ear Node Leaf (cm) 8.3 0.96 15Length of Ear Node Leaf (cm) 66.5 5.33 15 Number of Leaves above Top Ear5.0 0.38 15 Leaf Angle: (at anthesis, 2nd leaf above ear to 26.0 4.57 15stalk above leaf) (Degrees) *Leaf Color: Dark Green Munsell: 7.5GY44Leaf Sheath Pubescence: 1 = none to 9 = like peach fuzz 3 5. TASSEL:Number of Primary Lateral Branches 4.5 1.25 15 Branch Angle from CentralSpike 26.3 3.71 15 Tassel Length: (from peduncle node to tassel tip),(cm). 48.5 3.70 15 Pollen Shed: 0 = male sterile, 9 = heavy shed 4*Anther Color: Light Green Munsell: 2.5GY78 *Glume Color: Med. GreenMunsell: 5GY78 *Bar Glumes (glume bands): 1 = absent, 2 = present 1Peduncle Length: (from top leaf node to lower florets or 18.5 3.64 15branches), (cm). VARIETY DESCRIPTION INFORMATION PHCWK AVG STDEV N 6a.EAR (Unhusked ear) *Silk color: Pale Yellow Munsell: 7.5Y8.56 (3 daysafter silk emergence) *Fresh husk color: Med. Green Munsell: 7.5GY56*Dry husk color: Buff Munsell: 2.5Y8.54 (65 days after 50% silking) Earposition at dry husk stage: 1 = upright, 2 = horizontal, 2 3 = pendantHusk Tightness: (1 = very loose, 9 = very tight) 5 Husk Extension (atharvest): 1 = short(ears exposed), 2 2 = medium (<8 cm), 3 = long (8-10cm), 4 = v. long (>10 cm) 6b. EAR (Husked ear data) Ear Length (cm):16.7 0.49 15 Ear Diameter at mid-point (mm) 37.4 1.18 15 Ear Weight(gm): 119.9 8.19 15 Number of Kernel Rows: 12.7 1.45 15 Kernel Rows: 1 =indistinct, 2 = distinct 2 Row Alignment: 1 = straight, 2 = slightlycurved, 3 = spiral 2 Shank Length (cm): 13.1 1.33 15 Ear Taper: 1 =slight cylind., 2 = average, 3 = extreme 2 7. KERNEL (Dried): KernelLength (mm): 10.1 0.46 15 Kernel Width (mm): 8.1 0.35 15 KernelThickness (mm): 4.8 0.68 15 Round Kernels (shape grade) (%) 43.7 8.72 3Aleurone Color Pattern: 1 = homozygous, 2 = segregating 1 *AleuroneColor: Yellow Munsell: 10YR612 *Hard Endo. Color: Yellow Munsell:10YR610 Endosperm Type: 3 1 = sweet (su1), 2 = extra sweet (sh2), 3 =normal starch, 4 = high amylose starch, 5 = waxy starch, 6 = highprotein, 7 = high lysine, 8 = super sweet (se), 9 = high oil, 10 = otherWeight per 100 Kernels (unsized sample) (gm): 25.7 0.58 3 8. COB: *CobDiameter at mid-point (mm): 21.9 1.06 15 *Cob Color: Red Munsell:2.5YR38 10. DISEASE RESISTANCE: (Rate from 1 = most-susceptable to 9 =most-resistant. Leave blank if not tested, leave race or strain optionsblank if polygenic.) A. LEAF BLIGHTS, WILTS, AND LOCAL INFECTIONDISEASES Anthracnose Leaf Blight (Colletotrichum graminicola) CommonRust (Puccinia sorghi) Common Smut (Ustilago maydis) 7 Eyespot(Kabatiella zeae) Gross's Wilt (Clavibacter michiganense spp.nebraskense) 4 Gray Leaf Spot (Cercospora zeae-maydis) HelminthosporiumLeaf Spot (Bipolaris zeicola) Race: 6 Northern Leaf Blight (Exserohilumturcicum) Race: Southern Leaf Blight (Bipolaris maydis) Race: SouthernRust (Puccinia polysora) Stewart's Wilt (Erwinia stewartii) Other(Specify):            B. SYSTEMIC DISEASES Corn Lethal Necrosis (MCMVand MDMV) 9 Head Smut (Sphacelotheca reiliana) Maize Chlorotic DwarfVirus (MDV) Maize Chlorotic Mottle Virus (MCMV) 7 Maize Dwarf MosaicVirus (MDMV) Sorghum Downy Mildew of Corn (Peronosclerospora sorghi)Other (Specify):            C. STALK ROTS 4 Anthracnose Stalk Rot(Colletotrichum graminicola) Diplodia Stalk Rot (Stenocarpella maydis)Fusarium Stalk Rot (Fusarium moniliforme) Gibberella Stalk Rot(Gibberella zeae) Other (Specify):            D. EAR AND KERNEL ROTSAspergillus Ear and Kernel Rot (Aspergillus flavus) 4 Diplodia Ear Rot(Stenocarpella maydis) Fusarium Ear and Kernel Rot (Fusariummoniliforme) Gibberella Ear Rot (Gibberella zeae) Other (Specify):           11. INSECT RESISTANCE: (Rate from 1 = most-suscept. to 9 =most-resist., leave blank if not tested.) Corn Worm (Helicoverpa zea)    Leaf Feeding     Silk Feeding     Ear Damage Corn Leaf Aphid(Rophalosiphum maydis) Corn Sap Beetle (Capophilus dimidiatus) EuropeanCorn Borer (Ostrinia nubilalis) 1st. Generation (Typically whorl leaffeeding) 2nd. Generation (Typically leaf sheath-collar feeding)    Stalk Tunneling     cm tunneled/plant Fall armyworm (Spodopterafruqiperda)     Leaf Feeding     Silk Feeding     mg larval wt. MaizeWeevil (Sitophilus zeamaize) Northern Rootworm (Diabrotica barberi)Southern Rootworm (Diabrotica undecimpunctata) Southwestern Corn Borer(Diatreaea grandiosella)     Leaf Feeding     Stalk Tunneling     cmtunneled/plant Two-spotted Spider Mite (Tetranychus utricae) WesternRootworm (Diabrotica virgifrea virgifrea) Other (Specify):           12. AGRONOMIC TRAITS: Staygreen (at 65 days after anthesis; rate from1-worst to 9-excellent) % Dropped Ears (at 65 days after anthesis) %Pre-anthesis Brittle Snapping % Pre-anthesis Root Lodging %Post-anthesis Root Lodging (at 65 days after anthesis) % Post-anthesisStalk Lodging 7,891.0 Kg/ha (Yield at 12-13% grain moisture)*Munsell Glossy Book of Color, (A standard color reference). KollmorgenInst. Corp. New Windsor, NY.

TABLE 2 SSR PROFILE OF PHCWK Bin # Marker Name Base Pairs 1.01 BNLG1014116.16 1.01 UMC2215 144.91 1.02 BNLG1007 134.75 1.02 BNLG1083 221.661.02 BNLG1127 114.28 1.02 BNLG1953 248.02 1.03 BNGL439 232.18 1.03PHI109275 132.76 1.04 BNLG1016 251.73 1.04 BNLG2086 225.05 1.05 BNLG1832233.43 1.05 BNLG1886 147.73 1.06 BNLG1057 247.08 1.06 BNLG1615 219.231.07 BNLG1556 178.52 1.09 BNLG1331 119.4 1.09 BNLG1720 236.57 1.09PHI011 212.86 1.09 UMC1306 134.6 1.1 PHI308707 117 1.11 PHI064 82.6 1.11PHI227562 322.63 1.11 PHI265454 217.53 1.11 UMC1630 185.46 2.01 PHI96100280.07 2.01 UMC1227 139.52 2.02 BNLG1017 195.39 2.02 UMC1265 302.3 2.03BNLG1064 200.59 2.03 PHI109642 147.9 2.04 PHI083 129.02 2.04 UMC1326142.96 2.05 UMC1275 314.26 2.06 BNLG1036 163.26 2.06 BNLG1138 218.132.06 BNLG1396 133.44 2.06 BNLG1831 190.13 2.07 UMC1560 152.99 2.08BNLG1141 180.68 2.08 BNLG1258 177.15 2.08 BNLG1940 208.48 2.08 PHI435417217.86 2.08 UMC1049 129.76 2.09 BNLG1520 285.99 2.09 UMC1736 284.61 2.1PHI101049 226.4 3 PHI453121 211.71 3.01 PHI104127 169.51 3.01 PHI404206298.76 3.02 BNLG1647 179.81 3.02 PHI243966 211.17 3.04 BNLG1452 131.53.04 BNLG1638 198.86 3.04 BNLG2241 142.46 3.05 BNLG1035 101.07 3.05PHI073 185.61 3.06 BNLG1160 208.68 3.06 BNLG1951 124.93 3.06 PHI102228135.66 3.09 BNLG1496 233.34 3.1 UMC1136 145.43 4 PHI072 139.92 4.01PHI295450 197.06 4.03 ADH2 117.96 4.05 BNLG1159 145.81 4.05 BNLG1265192.5 4.05 BNLG1755 240.32 4.05 BNLG1937 237.87 4.05 UMC1175 282.21 4.07BNLG1784 229.46 4.07 UMC2038 135.48 4.11 BNLG1890 200.68 4.11 PHI076170.08 5.03 PHI109188 161.35 5.04 BNGL653 151.47 5.04 BNLG1208 118.85.04 BNLG653 152.68 5.05 PHI333597 216.23 5.05 UMC2386 124.6 5.06 PHI085256.45 5.07 BNLG1118 82.62 5.07 BNLG1346 175.42 5.07 BNLG1711 177.096.01 BNLG1422 215.98 6.04 UMC2317 129.67 6.05 BNLG1174 222.8 6.06UMC1463 301.61 6.07 BNLG1740 236.52 6.07 PHI299852 119.8 7 BNLG2132222.7 7.01 UMC1159 227.99 7.02 BNLG1094 153.5 7.02 PHI034 119.84 7.02UMC2327 130.67 7.03 BNLG1070 145.52 7.03 BNLG2271 233.62 7.03 UMC1713138.75 7.04 PHI328175 128.12 7.06 PHI116 169.95 8.01 UMC1075 260.75 8.03BNLG1863 272.29 8.03 PHI100175 136.76 8.03 PHI115 303.03 8.03 PHI12193.25 8.04 BNLG2046 320.53 8.05 BNLG1176 225.95 8.06 UMC1149 216.54 8.07BNLG1065 237.06 8.08 BNLG1056 94.63 8.08 PHI015 82.71 8.09 PHI233376135.77 8.09 UMC1663 201.45 9.01 BNLG1810 211.05 9.01 BNLG2122 221.369.01 PHI033 249.12 9.01 UMC1867 238.42 9.03 PHI079 187.4 9.04 BNLG1012161.56 9.06 PHI448880 176.97 9.08 BNLG1129 290.49 10 PHI041 202.03 10.01UMC1291 138.69 10.02 BNLG1429 205.1 10.02 PHI059 152.96 10.03 BNLG1079172.81 10.03 UMC1037 228.71 10.04 PHI062 161.16 10.05 BNLG1074 184.1810.07 BNLG1450 184.87

TABLE 3A PAIRED INBRED COMPARISON REPORT Variety #1: PHCWK Variety #2:PH5TG YIELD YIELD MST EGRWTH ESTCNT TILLER BU/A 56# BU/A 56# PCT SCORECOUNT PCT Stat ABS % MN ABS ABS ABS ABS Mean1 125.7 133.7 14.7 5.6 22.93.7 Mean2 105.8 109.9 15.5 6.2 21.5 9.1 Locs 8 8 8 15 17 12 Reps 16 1616 15 18 12 Diff 19.9 23.8 0.8 −0.6 1.4 5.3 Prob 0.046 0.047 0.521 0.0230.243 0.390 GDUSHD GDUSLK POLWT POLWT TASBLS TASSZ GDU GDU VALUE VALUESCORE SCORE Stat ABS ABS ABS % MN ABS ABS Mean1 118.4 119.6 68.5 53.59.0 4.1 Mean2 121.9 126.1 103.7 81.5 9.0 4.4 Locs 38 38 15 15 2 32 Reps38 38 30 30 3 32 Diff −3.5 −6.5 −35.1 −28.1 0.0 −0.3 Prob 0.000 0.0000.000 0.000 1.000 0.070 PLTHT EARHT STAGRN STKLDG SCTGRN EARMLD CM CMSCORE % NOT SCORE SCORE Stat ABS ABS ABS ABS ABS ABS Mean1 223.4 92.23.7 65.0 8.5 7.3 Mean2 204.7 83.3 4.0 80.0 6.5 8.7 Locs 21 8 3 1 6 3Reps 21 8 3 1 6 3 Diff 18.7 8.9 −0.3 −15.0 2.0 −1.3 Prob 0.000 0.0740.742 — 0.041 0.270 BARPLT GLFSPT NLFBLT ANTROT FUSERS EYESPT % NOTSCORE SCORE SCORE SCORE SCORE Stat ABS ABS ABS ABS ABS ABS Mean1 98.83.5 6.0 4.0 7.0 4.0 Mean2 95.3 4.5 7.0 8.0 8.8 5.5 Locs 14 1 1 1 4 1Reps 14 2 1 2 4 2 Diff 3.5 −1.0 −1.0 −4.0 −1.8 −1.5 Prob 0.046 — — —0.035 — HD SMT COMRST CLDTST CLDTST KSZDCD % ERTLPN LRTLPN SCORE PCT PCTPCT NOT % NOT % NOT Stat ABS ABS % MN ABS ABS ABS ABS Mean1 7.0 90.098.2 3.4 100.0 100.0 95.0 Mean2 7.0 90.6 99.0 7.4 100.0 100.0 95.0 Locs1 13 13 13 1 2 2 Reps 1 13 13 13 2 2 2 Diff 0.0 −0.6 −0.8 −4.0 0.0 0.00.0 Prob — 0.680 0.653 0.001 — 1.000 1.000

TABLE 3B PAIRED INBRED COMPARISON REPORT Variety #1: PHCWK Variety #2:PH1CN EGRWTH ESTCNT TILLER GDUSHD GDUSLK SCORE COUNT PCT GDU GDU StatABS ABS ABS ABS ABS Mean1 6.5 22.0 1.1 120.1 120.4 Mean2 5.0 14.0 0.0128.9 130.4 Locs 2 2 3 7 7 Reps 2 2 3 7 7 Diff 1.5 8.0 −1.1 −8.7 −10.0Prob 0.205 0.500 0.423 0.009 0.003 TASBLS TASSZ PLTHT EARHT STAGRN SCORESCORE CM CM SCORE Stat ABS ABS ABS ABS ABS Mean1 9.0 4.7 222.3 89.4 1.0Mean2 9.0 5.0 204.6 81.9 2.0 Locs 2 7 5 2 1 Reps 2 7 5 2 1 Diff 0.0 −0.317.7 7.5 −1.0 Prob 1.000 0.172 0.009 0.500 — BARPLT ERTLPN LRTLPN % NOT% NOT % NOT Stat ABS ABS ABS Mean1 100.0 100.0 70.0 Mean2 96.7 100.0100.0 Locs 4 1 1 Reps 4 1 1 Diff 3.3 0.0 −30.0 Prob 0.234 — —

TABLE 3C PAIRED INBRED COMPARISON REPORT Variety #1: PHCWK Variety #2:PHAA0 YIELD YIELD EGRWTH ESTCNT TILLER BU/A 56# BU/A 56# MST PCT SCORECOUNT PCT Stat ABS % MN ABS ABS ABS ABS Mean1 125.7 133.7 14.7 5.6 22.93.7 Mean2 118.0 125.3 14.9 6.4 20.1 0.0 Locs 8 8 8 15 17 12 Reps 16 1616 15 18 12 Diff 7.7 8.4 0.2 −0.8 2.9 −3.7 Prob 0.038 0.051 0.852 0.0030.011 0.154 GDUSHD GDUSLK POLWT POLWT TASBLS TASSZ GDU GDU VALUE VALUESCORE SCORE Stat ABS ABS ABS % MN ABS ABS Mean1 118.4 119.6 74.8 58.99.0 4.1 Mean2 117.3 118.8 82.3 63.4 9.0 3.0 Locs 38 38 19 19 2 32 Reps38 38 36 36 3 32 Diff 1.0 0.8 −7.5 −4.5 0.0 1.1 Prob 0.096 0.164 0.2580.376 1.000 0.000 PLTHT EARHT STAGRN STKLDG SCTGRN EARMLD CM CM SCORE %NOT SCORE SCORE Stat ABS ABS ABS ABS ABS ABS Mean1 223.4 92.2 3.7 65.08.5 7.3 Mean2 192.4 75.4 4.3 36.8 8.3 8.0 Locs 21 8 3 1 6 3 Reps 21 8 31 6 3 Diff 31.0 16.8 −0.7 28.2 0.2 −0.7 Prob 0.000 0.006 0.529 — 0.6110.423 BARPLT GLFSPT NLFBLT ANTROT FUSERS EYESPT % NOT SCORE SCORE SCORESCORE SCORE Stat ABS ABS ABS ABS ABS ABS Mean1 98.8 3.5 6.0 4.0 7.0 4.0Mean2 98.5 3.5 7.0 8.0 8.5 5.5 Locs 14 1 1 1 4 1 Reps 14 2 1 2 4 2 Diff0.2 0.0 −1.0 −4.0 −1.5 −1.5 Prob 0.707 — — — 0.103 — HD COMRST CLDTSTCLDTST KSZDCD SMT ERTLPN LRTLPN SCORE PCT PCT PCT % NOT % NOT % NOT StatABS ABS % MN ABS ABS ABS ABS Mean1 7.0 89.2 97.9 2.8 100.0 100.0 95.0Mean2 8.0 91.7 100.7 6.9 100.0 100.0 95.0 Locs 1 12 12 12 1 2 2 Reps 112 12 12 2 2 2 Diff −1.0 −2.5 −2.8 −4.2 0.0 0.0 0.0 Prob — 0.215 0.2110.001 — 1.000 1.000

TABLE 3D PAIRED INBRED COMPARISON REPORT Variety #1: PHCWK Variety #2:PH75K YIELD YIELD MST EGRWTH ESTCNT TILLER BU/A 56# BU/A 56# PCT SCORECOUNT PCT Stat ABS % MN ABS ABS ABS ABS Mean1 126.6 133.3 14.5 5.7 22.83.2 Mean2 102.5 106.8 14.4 6.1 21.8 1.2 Locs 4 4 4 17 18 15 Reps 8 8 817 18 15 Diff 24.0 26.5 0.0 −0.4 0.9 −2.0 Prob 0.012 0.019 0.921 0.1100.456 0.386 GDUSLK TASBLS TASSZ PLTHT EARHT GDUSHD GDU GDU SCORE SCORECM CM Stat ABS ABS ABS ABS ABS ABS Mean1 118.6 119.8 9.0 4.2 223.2 91.6Mean2 119.8 120.1 9.0 4.3 188.4 77.0 Locs 45 45 3 39 26 10 Reps 45 45 339 26 10 Diff −1.2 −0.3 0.0 −0.1 34.8 14.7 Prob 0.028 0.505 1.000 0.5840.000 0.010 STAGRN STKLDG SCTGRN EARMLD BARPLT GLFSPT SCORE % NOT SCORESCORE % NOT SCORE Stat ABS ABS ABS ABS ABS ABS Mean1 3.0 65.0 8.5 6.599.0 3.5 Mean2 3.3 85.0 7.0 7.5 94.1 3.0 Locs 4 1 6 2 18 1 Reps 4 1 6 218 2 Diff −0.3 −20.0 1.5 −1.0 5.0 0.5 Prob 0.391 — 0.107 0.500 0.027 —NLFBLT ANTROT FUSERS EYESPT COMRST CLDTST SCORE SCORE SCORE SCORE SCOREPCT Stat ABS ABS ABS ABS ABS ABS Mean1 6.0 4.0 7.0 4.0 7.0 86.8 Mean27.0 8.5 7.8 5.5 8.0 92.8 Locs 1 1 4 1 1 4 Reps 1 2 4 2 1 4 Diff −1.0−4.5 −0.8 −1.5 −1.0 −6.0 Prob — — 0.215 — — 0.078 ERTLPN LRTLPN CLDTSTKSZDCD HD SMT % NOT % NOT % NOT Stat PCT % MN PCT ABS ABS ABS ABS Mean196.2 2.5 100.0 100.0 86.7 Mean2 102.9 4.3 100.0 95.3 73.3 Locs 4 4 1 3 3Reps 4 4 2 3 3 Diff −6.7 −1.8 0.0 4.7 13.3 Prob 0.082 0.188 — 0.4230.732

TABLE 4 GENERAL COMBINING ABILITY REPORT PHCWK PRM Day ABS Mean 92 PRMDay ABS Reps 2969 PRMSHD Day ABS Mean 91 PRMSHD Day ABS Reps 2989 YIELDbu/a 56# ABS Mean 162.7 YIELD bu/a 56# ABS Reps 1467 YIELD bu/a 56# ABSYears 3 YIELD bu/a 56# % MN Mean 100.9 YIELD bu/a 56# % MN Reps 1467 MSTpct ABS Mean 23 MST pct ABS Reps 1477 MST pct % MN Mean 99.9 MST pct %MN Reps 1477 STLPCN % NOT % MN Mean 93 STLPCN % NOT % MN Reps 501 STLLPN% NOT % MN Mean 89 STLLPN % NOT % MN Reps 297 ERTLPN % NOT % MN Mean 119ERTLPN % NOT % MN Reps 42 LRTLPN % NOT % MN Mean 99 LRTLPN % NOT % MNReps 145 TSTWT lb/bu % MN Mean 100.9 TSTWT lb/bu % MN Reps 883 STKCNTcount % MN Mean 100 STKCNT count % MN Reps 2569 PLTHT in % MN Mean 102PLTHT in % MN Reps 641 EARHT in % MN Mean 102 EARHT in % MN Reps 638BRTSTK % NOT % MN Mean 104 BRTSTK % NOT % MN Reps 188 GLFSPT score ABSMean 2 GLFSPT score ABS Reps 6 STAGRN score ABS Mean 5 STAGRN score ABSReps 510 HSKCVR score ABS Mean 6 HSKCVR score ABS Reps 105

TABLE 5A INBREDS IN HYBRID COMBINATION REPORT Variety #1: HYBRIDCONTAINING PHCWK Variety #2: 38R92 YIELD YIELD MST EGRWTH ESTCNT GDUSHDBU/A 56# BU/A 56# PCT SCORE COUNT GDU Stat ABS % MN % MN % MN % MN % MNMean1 164.4 100.3 98.2 95.7 89.5 98.5 Mean2 165.2 100.9 100.9 102.7100.4 98.9 Locs 14 14 14 16 6 12 Reps 27 27 27 32 12 19 Diff −0.8 −0.62.7 −7.0 −10.9 −0.3 Prob 0.709 0.644 0.031 0.239 0.030 0.553 GDUSLKSTKCNT STAGRN TSTWT GDU COUNT PLTHT CM EARHT CM SCORE LB/BU Stat % MN %MN % MN % MN % MN ABS Mean1 98.8 97.4 105.3 106.0 82.1 52.5 Mean2 99.1100.3 96.2 99.7 104.5 51.4 Locs 6 40 8 8 7 10 Reps 8 78 15 15 13 20 Diff−0.3 −2.8 9.1 6.3 −22.3 1.1 Prob 0.620 0.000 0.000 0.010 0.004 0.036ECB1LF ECB2SC HSKCVR GIBROT BRTSTK LRTLPN SCORE SCORE SCORE SCORE % NOT% NOT Stat ABS ABS ABS ABS ABS ABS Mean1 9.0 8.7 7.0 3.0 93.1 95.0 Mean26.0 4.7 4.5 2.0 86.4 100.0 Locs 1 3 1 1 4 1 Reps 2 6 2 2 8 2 Diff 3.04.0 2.5 1.0 6.7 −5.0 Prob — 0.015 — — 0.484 —

TABLE 5B INBREDS IN HYBRID COMBINATION REPORT Variety #1: HYBRIDCONTAINING PHCWK Variety #2: 38G60 YIELD YIELD MST EGRWTH ESTCNT GDUSHDBU/A 56# BU/A 56# PCT SCORE COUNT GDU Stat ABS % MN % MN % MN % MN % MNMean1 157.7 101.8 99.8 96.4 94.8 98.8 Mean2 156.4 100.5 97.0 86.6 109.9100.2 Locs 36 36 36 10 14 27 Reps 74 74 75 20 31 48 Diff 1.3 1.2 −2.89.8 −15.1 −1.3 Prob 0.490 0.338 0.033 0.239 0.019 0.000 GDUSLK STKCNTSTAGRN STKLDG GDU COUNT PLTHT CM EARHT CM SCORE % NOT Stat % MN % MN %MN % MN % MN % MN Mean1 98.5 100.0 101.5 99.5 95.4 98.8 Mean2 101.0101.3 102.0 98.5 105.3 100.1 Locs 14 69 15 15 15 2 Reps 19 135 32 32 324 Diff −2.4 −1.3 −0.5 0.9 −9.9 −1.3 Prob 0.001 0.001 0.578 0.667 0.2730.500 TSTWT ANTROT FUSERS GIBERS ECB2SC HSKCVR LB/BU SCORE SCORE SCORESCORE SCORE Stat ABS ABS ABS ABS ABS ABS Mean1 53.4 2.0 9.0 8.0 4.9 5.9Mean2 51.6 5.5 9.0 7.5 3.5 5.9 Locs 24 1 1 2 4 8 Reps 50 2 2 4 10 16Diff 1.8 −3.5 0.0 0.5 1.4 −0.1 Prob 0.000 — — 0.500 0.325 0.882 GIBROTERTLPN SCORE BRTSTK HD SMT % NOT % NOT LRTLPN Stat ABS % NOT ABS ABS ABS% NOT ABS Mean1 2.0 94.3 71.3 89.0 100.0 Mean2 3.0 83.3 98.3 85.4 90.3Locs 1 5 3 5 3 Reps 2 10 4 10 5 Diff −1.0 11.0 −27.0 3.6 9.7 Prob —0.260 0.209 0.681 0.237

TABLE 5C INBREDS IN HYBRID COMBINATION REPORT Variety #1: HYBRIDCONTAINING PHCWK Variety #2: 38R69 YIELD YIELD MST EGRWTH ESTCNT GDUSHDBU/A 56# BU/A 56# PCT SCORE COUNT GDU Stat ABS % MN % MN % MN % MN % MNMean1 163.5 100.6 98.2 93.9 97.5 98.7 Mean2 160.1 98.5 100.0 104.7 96.098.5 Locs 48 48 48 10 12 27 Reps 72 72 72 18 25 40 Diff 3.4 2.2 1.8−10.9 1.6 0.2 Prob 0.147 0.120 0.090 0.031 0.771 0.607 GDUSLK STKCNTSTAGRN STKLDG GDU COUNT PLTHT CM EARHT CM SCORE % NOT Stat % MN % MN %MN % MN % MN % MN Mean1 98.5 100.0 101.7 99.9 94.6 98.8 Mean2 97.6 99.194.7 100.0 107.2 100.1 Locs 14 79 15 15 15 2 Reps 19 131 25 25 27 4 Diff0.9 0.8 7.0 −0.1 −12.5 −1.3 Prob 0.078 0.054 0.000 0.956 0.030 0.500TSTWT NLFBLT ANTROT FUSERS GIBERS ECB2SC LB/BU SCORE SCORE SCORE SCORESCORE Stat ABS ABS ABS ABS ABS ABS Mean1 53.9 1.0 2.0 9.0 8.0 4.7 Mean252.6 2.5 2.5 8.0 6.0 3.8 Locs 19 2 1 1 2 8 Reps 33 2 2 2 4 14 Diff 1.3−1.5 −0.5 1.0 2.0 0.9 Prob 0.000 0.205 — — 0.410 0.471 HD HSKCVR GIBROTBRTSTK SMT ERTLPN LRTLPN SCORE SCORE % NOT % NOT % NOT % NOT Stat ABSABS ABS ABS ABS ABS Mean1 5.9 2.0 97.1 75.8 85.8 100.0 Mean2 4.2 1.087.1 95.4 55.3 99.2 Locs 7 1 4 4 6 3 Reps 14 2 8 5 11 5 Diff 1.6 1.0 9.9−19.6 30.6 0.8 Prob 0.039 — 0.246 0.153 0.016 0.423

TABLE 5D INBREDS IN HYBRID COMBINATION REPORT Variety #1: HYBRIDCONTAINING PHCWK Variety #2: 38R92 YIELD YIELD MST EGRWTH ESTCNT GDUSHDBU/A 56# BU/A 56# PCT SCORE COUNT GDU Stat ABS % MN % MN % MN % MN % MNMean1 158.9 100.8 98.4 98.6 94.1 98.8 Mean2 156.7 99.5 103.4 94.5 92.798.9 Locs 48 48 48 26 20 38 Reps 92 92 93 52 43 64 Diff 2.2 1.3 5.0 4.11.5 0.0 Prob 0.154 0.207 0.000 0.336 0.731 0.883 GDUSLK STKCNT STAGRNSTKLDG GDU COUNT PLTHT CM EARHT CM SCORE % NOT Stat % MN % MN % MN % MN% MN % MN Mean1 98.7 99.2 102.4 100.6 92.5 98.8 Mean2 99.0 99.2 94.896.8 112.9 100.3 Locs 20 101 22 22 22 2 Reps 27 190 44 44 44 4 Diff −0.30.0 7.6 3.8 −20.4 −1.5 Prob 0.301 0.999 0.000 0.010 0.000 0.677 TSTWTANTROT FUSERS GIBERS ECB1LF ECB2SC LB/BU SCORE SCORE SCORE SCORE SCOREStat ABS ABS ABS ABS ABS ABS Mean1 52.8 2.0 9.0 8.0 6.0 5.3 Mean2 52.23.5 9.0 7.5 6.0 4.0 Locs 33 1 1 2 1 7 Reps 66 2 2 4 2 16 Diff 0.7 −1.50.0 0.5 0.0 1.3 Prob 0.011 — — 1.000 — 0.146 HD HSKCVR GIBROT BRTSTK SMTERTLPN LRTLPN SCORE SCORE % NOT % NOT % NOT % NOT Stat ABS ABS ABS ABSABS ABS Mean1 6.0 3.0 95.7 71.3 89.0 98.8 Mean2 5.7 2.0 87.6 95.3 63.599.6 Locs 9 2 9 3 5 4 Reps 18 4 17 4 10 7 Diff 0.3 1.0 8.1 −24.0 25.5−0.9 Prob 0.621 0.500 0.066 0.240 0.082 0.581

TABLE 5E INBREDS IN HYBRID COMBINATION REPORT Variety #1: HYBRIDCONTAINING PHCWK Variety #2: 39K40 YIELD YIELD MST EGRWTH ESTCNT GDUSHDBU/A 56# BU/A 56# PCT SCORE COUNT GDU Stat ABS % MN % MN % MN % MN % MNMean1 179.8 109.1 102.7 91.7 96.0 99.6 Mean2 157.5 94.7 97.4 92.5 105.7100.3 Locs 19 19 19 4 11 17 Reps 28 28 28 7 21 24 Diff 22.3 14.4 −5.2−0.8 −9.7 −0.8 Prob 0.000 0.000 0.023 0.912 0.093 0.127 GDUSLK STKCNTSTAGRN TSTWT GDU COUNT PLTHT CM EARHT CM SCORE LB/BU Stat % MN % MN % MN% MN % MN ABS Mean1 99.1 99.8 101.2 98.2 108.0 54.7 Mean2 100.2 101.098.5 97.4 95.7 53.8 Locs 10 35 8 8 10 13 Reps 13 49 13 13 15 21 Diff−1.1 −1.3 2.7 0.8 12.4 0.9 Prob 0.120 0.176 0.097 0.785 0.276 0.137ECB2SC HSKCVR LRTLPN SCORE SCORE BRTSTK % NOT ERTLPN % NOT % NOT StatABS ABS ABS ABS ABS Mean1 6.0 5.2 99.2 88.8 90.0 Mean2 3.3 5.5 100.050.8 90.0 Locs 2 5 2 4 3 Reps 5 8 3 8 3 Diff 2.7 −0.3 −0.8 38.0 0.0 Prob0.458 0.529 0.500 0.159 1.000

TABLE 5F INBREDS IN HYBRID COMBINATION REPORT Variety #1: HYBRIDCONTAINING PHCWK Variety #2: 38G60 GDUSHD STKCNT PLTHT EARHT GDU COUNTCM CM Stat % MN % MN % MN % MN Mean1 99.2 99.7 105.1 102.9 Mean2 100.2100.7 107.3 99.9 Locs 1 7 1 1 Reps 2 15 2 2 Diff −1.0 −1.0 −2.2 3.1 Prob— 0.595 — —

TABLE 5G INBREDS IN HYBRID COMBINATION REPORT Variety #1: HYBRIDCONTAINING PHCWK Variety #2: 38R69 GDUSHD STKCNT PLTHT EARHT GDU COUNTCM CM Stat % MN % MN % MN % MN Mean1 99.2 99.7 105.1 102.9 Mean2 101.196.4 92.7 101.9 Locs 1 7 1 1 Reps 1 14 2 2 Diff −1.9 3.3 12.4 1.0 Prob —0.206 — —

All publications, patents and patent applications mentioned in thespecification are indicative of the level of those skilled in the art towhich this invention pertains. All such publications, patents and patentapplications are incorporated by reference herein for the purpose citedto the same extent as if each was specifically and individuallyindicated to be incorporated by reference herein.

The foregoing invention has been described in detail by way ofillustration and example for purposes of clarity and understanding. Asis readily apparent to one skilled in the art, the foregoing are onlysome of the methods and compositions that illustrate the embodiments ofthe foregoing invention. It will be apparent to those of ordinary skillin the art that variations, changes, modifications and alterations maybe applied to the compositions and/or methods described herein withoutdeparting from the true spirit, concept and scope of the invention.

1. A seed comprising at least one set of the chromosomes of maize inbredline PHCWK, representative seed of said line having been deposited underATCC Accession No. PTA-6350, wherein said chromosomes comprise all ofthe alleles of inbred line PHCWK at the SSR loci listed in Table
 2. 2. Amaize plant produced by growing the seed of claim
 1. 3. A maize plantpart of the maize plant of claim
 2. 4. The seed of claim 1, wherein saidseed is an F1 hybrid maize seed produced by crossing a plant of maizeinbred line PHCWK with a different maize plant and harvesting theresultant F1 hybrid maize seed.
 5. A maize plant produced by growing theF1 hybrid maize seed of claim
 4. 6. A maize plant part of the maizeplant of claim
 5. 7. An F1 hybrid maize seed comprising an inbred cornplant cell of inbred maize line PHCWK, representative seed of said linehaving been deposited under ATCC Accession No. PTA-6350.
 8. A maizeplant produced by growing the F1 hybrid maize seed of claim
 7. 9. The F1hybrid maize seed of claim 7 wherein the inbred corn plant cellcomprises two sets of chromosomes of maize inbred line PHCWK, whereinsaid chromosomes comprise all of the alleles of inbred line PHCWK at theSSR loci listed in Table
 2. 10. A maize plant produced by growing the F1hybrid maize seed of claim
 9. 11. A process of introducing a desiredtrait into maize inbred line PHCWK comprising: (a) crossing PHCWK plantsgrown from PHCWK seed, representative seed of which has been depositedunder ATCC Accession No: PTA-6350, with plants of another maize linethat comprise a desired trait to produce F1 progeny plants, wherein thedesired trait is selected from the group consisting of waxy starch, malesterility, herbicide resistance, insect resistance, bacterial diseaseresistance, fungal disease resistance, and viral disease resistance; (b)selecting F1 progeny plants that have the desired trait to produceselected F1 progeny plants; (c) crossing the selected progeny plantswith the PHCWK plants to produce backcross progeny plants; (d) selectingfor backcross progeny plants that have the desired trait and the allelesof inbred line PHCWK at the SSR loci listed in Table 2 to produceselected backcross progeny plants; and (e) repeating steps (c) and (d)to produce backcross progeny plants that comprise the desired trait andcomprise at least 95% of the alleles of inbred line PHCWK at the SSRloci listed in Table
 2. 12. A plant produced by the process of claim 11,wherein the plant comprises at least 95% of the alleles of inbred linePHCWK at the SSR loci listed in Table 2.